Help support Khan Academy

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Kind: captions
Language: en

00:00:00.200 --> 00:00:02.490
- Hi, everyone. Sal Khan
here from Khan Academy.

00:00:02.490 --> 00:00:03.490
And I just wanted to remind you

00:00:03.490 --> 00:00:06.230
that we are a not-for-profit
and we can only exist

00:00:06.230 --> 00:00:09.100
through donations from
folks like yourself.

00:00:09.100 --> 00:00:12.410
Our goal is for everyone
to reach their potential.

00:00:12.410 --> 00:00:14.870
Potential is everywhere.

00:00:14.870 --> 00:00:17.020
Unfortunately, access is not.

00:00:17.020 --> 00:00:20.290
And that's what Khan
Academy exists to change.

00:00:20.290 --> 00:00:23.970
We are trying to reach tens
of millions of students

00:00:23.970 --> 00:00:26.100
around the world, students in historically

00:00:26.100 --> 00:00:27.640
under-resourced communities,

00:00:27.640 --> 00:00:29.390
working with school districts in the US,

00:00:29.390 --> 00:00:32.800
working with stakeholders
from around the planet

00:00:32.800 --> 00:00:36.510
to make sure that students have
a way to fill in their gaps,

00:00:36.510 --> 00:00:38.180
learn at their own time and pace,

00:00:38.180 --> 00:00:41.850
have access to truly
rigorous course materials.

00:00:41.850 --> 00:00:44.890
So I encourage you to think
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The social return on
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we're about the budget
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but we reach already a chunk of humanity

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and we wanna reach many, many more,

00:00:54.520 --> 00:00:57.530
with over 140 million
registered users today

00:00:57.530 --> 00:01:00.000
and hopefully billions going forward.

00:01:00.000 --> 00:01:01.600
So please think about making a donation.

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If you've benefited from Khan Academy,

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you know from folks who've
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00:01:07.070 --> 00:01:09.320
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00:01:09.320 --> 00:01:12.180
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please think about making a donation.

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Thank you.

00:01:18.579 --> 00:01:21.162
(chimes trill)


Natural hazards

WEBVTT
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Language: en

00:00:00.110 --> 00:00:01.420
- [Instructor] Before I go to a new place,

00:00:01.420 --> 00:00:03.810
I try to do some thorough
research about it.

00:00:03.810 --> 00:00:05.140
What do I want to do there?

00:00:05.140 --> 00:00:06.970
What's the weather forecast?

00:00:06.970 --> 00:00:09.210
What's the chance that it might erupt?

00:00:09.210 --> 00:00:10.960
I learned this hard way recently.

00:00:10.960 --> 00:00:13.740
While preparing for a trip to
Mount Rainier National Park,

00:00:13.740 --> 00:00:15.390
I somehow missed that the mountain itself

00:00:15.390 --> 00:00:17.160
is actually a volcano.

00:00:17.160 --> 00:00:19.010
Though it hasn't erupted
in over a century,

00:00:19.010 --> 00:00:21.030
it has the potential to do so again,

00:00:21.030 --> 00:00:22.670
something that it would
have been nice to know

00:00:22.670 --> 00:00:25.180
more than a week before
I left for my vacation.

00:00:25.180 --> 00:00:26.961
Volcanoes are one of the
most dramatic examples

00:00:26.961 --> 00:00:28.932
of a natural hazard,

00:00:28.932 --> 00:00:32.100
a naturally occurring
phenomenon that can pose risks

00:00:32.100 --> 00:00:34.120
to humans and society.

00:00:34.120 --> 00:00:35.980
Natural hazards can be very dangerous

00:00:35.980 --> 00:00:36.960
for our communities.

00:00:36.960 --> 00:00:39.460
But scientists can help people
better understand the risks

00:00:39.460 --> 00:00:40.610
that may occur where they live

00:00:40.610 --> 00:00:43.810
so everyone can work together
to prepare safety guidelines.

00:00:43.810 --> 00:00:46.140
Different places experience
different natural hazards

00:00:46.140 --> 00:00:48.888
due to local geographic
or atmospheric conditions.

00:00:48.888 --> 00:00:52.540
For example, a storm on open
plains could spawn a tornado.

00:00:52.540 --> 00:00:54.410
Similarly, a storm over the ocean

00:00:54.410 --> 00:00:56.140
could grow into a hurricane or a cyclone

00:00:56.140 --> 00:00:58.310
by the time it reaches the coast.

00:00:58.310 --> 00:00:59.640
These coastal rainstorms,

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along with their colder
counterparts, blizzards,

00:01:01.900 --> 00:01:03.960
are the main natural
hazards that I may run into

00:01:03.960 --> 00:01:05.670
where I live in the mid-Atlantic.

00:01:05.670 --> 00:01:08.020
Too much rain or snow can
be dangerous, of course,

00:01:08.020 --> 00:01:09.770
but scientists have gotten pretty good

00:01:09.770 --> 00:01:11.630
at predicting weather conditions.

00:01:11.630 --> 00:01:13.750
Meteorologists use all
kinds of technologies

00:01:13.750 --> 00:01:16.200
to map where and when a storm may form.

00:01:16.200 --> 00:01:17.840
Orbiting satellites can take pictures

00:01:17.840 --> 00:01:19.780
of cloud patterns from above.

00:01:19.780 --> 00:01:21.220
Weather stations back on the surface

00:01:21.220 --> 00:01:23.240
can use electromagnetic wave fields

00:01:23.240 --> 00:01:24.740
measured through Doppler radar

00:01:24.740 --> 00:01:26.470
to determine how heavy rain is falling

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or how strong the wind is
blowing in those same clouds.

00:01:29.210 --> 00:01:31.660
They feed all of this and
other data into computer models

00:01:31.660 --> 00:01:33.740
that can help them predict
if the storm is severe enough

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to become a natural hazard.

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For example, this map
from the National Oceanic

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and Atmospheric Administration's
Weather Prediction Center

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shows where people can expect rainstorms,

00:01:41.833 --> 00:01:43.970
where others can expect snowstorms,

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and where those storms
may become powerful enough

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to pose risks.

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Despite great advances in our ability

00:01:50.400 --> 00:01:51.550
to predict natural hazards,

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there are some phenomena
that are less predictable,

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which can make them harder to prepare for.

00:01:56.000 --> 00:01:58.120
You see, the outer part
of Earth is made up

00:01:58.120 --> 00:02:01.230
of large moving pieces
called tectonic plates.

00:02:01.230 --> 00:02:03.460
These plates can grind or
slip against each other,

00:02:03.460 --> 00:02:06.650
releasing energy in the
form of seismic waves.

00:02:06.650 --> 00:02:07.483
Most of the time,

00:02:07.483 --> 00:02:09.360
we don't even notice
these tectonic movements.

00:02:09.360 --> 00:02:10.760
But especially along boundaries

00:02:10.760 --> 00:02:11.900
or fault lines in the plates,

00:02:11.900 --> 00:02:12.733
people may experience

00:02:12.733 --> 00:02:14.800
the ground-shaking tremors of earthquakes.

00:02:14.800 --> 00:02:16.470
Earthquakes can be especially dangerous

00:02:16.470 --> 00:02:17.770
in highly populated areas

00:02:17.770 --> 00:02:19.310
where they damage buildings, roads,

00:02:19.310 --> 00:02:21.530
and other forms of human infrastructure.

00:02:21.530 --> 00:02:24.190
Earthquakes are often associated
with volcanic activity,

00:02:24.190 --> 00:02:26.210
since volcanoes are often
found near boundaries

00:02:26.210 --> 00:02:28.270
and fault lines of the tectonic plates.

00:02:28.270 --> 00:02:31.240
As the plates move and magma
swells up to the surface,

00:02:31.240 --> 00:02:33.060
volcanic eruptions can release everything

00:02:33.060 --> 00:02:36.500
from clouds of gas or ash
to rivers of molten lava.

00:02:36.500 --> 00:02:38.630
An earthquake in one
location may even agitate

00:02:38.630 --> 00:02:41.100
large bodies of water enough
to generate a tsunami,

00:02:41.100 --> 00:02:42.614
a huge and powerful wave,

00:02:42.614 --> 00:02:44.820
along the coastline in another.

00:02:44.820 --> 00:02:46.343
Tsunamis can affect the local region

00:02:46.343 --> 00:02:48.920
as well as regions far away.

00:02:48.920 --> 00:02:51.350
Scientists can't predict
an intense earthquake,

00:02:51.350 --> 00:02:53.700
volcanic eruption, or
tsunami as effectively

00:02:53.700 --> 00:02:55.380
as they can a severe weather event.

00:02:55.380 --> 00:02:57.080
But they are working to better understand

00:02:57.080 --> 00:02:59.920
Earth's seismic activity
and when it poses a risk.

00:02:59.920 --> 00:03:02.180
For example, they use
tools like seismographs

00:03:02.180 --> 00:03:04.060
to determine when an
earthquake is happening

00:03:04.060 --> 00:03:06.170
and its strength or magnitude.

00:03:06.170 --> 00:03:08.360
Data from both minor and major tremors

00:03:08.360 --> 00:03:09.840
may help scientists figure out the signs

00:03:09.840 --> 00:03:11.060
that an earthquake is coming,

00:03:11.060 --> 00:03:13.350
giving communities along
fault lines an early warning

00:03:13.350 --> 00:03:15.050
to evacuate or brace themselves,

00:03:15.050 --> 00:03:17.640
rather than simply
reacting to the aftermath.

00:03:17.640 --> 00:03:19.720
Engineers can even use
the data they've recorded

00:03:19.720 --> 00:03:21.240
from past earthquakes to design buildings

00:03:21.240 --> 00:03:23.168
and other structures to
withstand the effects

00:03:23.168 --> 00:03:24.900
of future ones.

00:03:24.900 --> 00:03:27.010
Communicating what they've
learned may help places

00:03:27.010 --> 00:03:28.970
that experience seismic natural hazards

00:03:28.970 --> 00:03:30.540
to prepare far in advance,

00:03:30.540 --> 00:03:33.130
further reducing the risks that they face.

00:03:33.130 --> 00:03:35.390
Natural hazards can cause a lot of harm.

00:03:35.390 --> 00:03:37.310
But scientists are learning more every day

00:03:37.310 --> 00:03:38.490
about why they occur

00:03:38.490 --> 00:03:41.130
and how communities can remain resilient.

00:03:41.130 --> 00:03:43.890
For my trip, I studied up
on visiting a volcano zone

00:03:43.890 --> 00:03:46.200
and was relieved to find
that there's been no signs

00:03:46.200 --> 00:03:48.680
that Mount Rainier's
erupting any time soon.

00:03:48.680 --> 00:03:50.910
The whole experience really
reinforced the importance

00:03:50.910 --> 00:03:51.990
of being prepared.

00:03:51.990 --> 00:03:53.274
Even if natural hazards aren't common

00:03:53.274 --> 00:03:54.770
where you live or travel,

00:03:54.770 --> 00:03:57.020
having a preparedness plan
can help you stay safe

00:03:57.020 --> 00:03:58.600
in a scary situation.

00:03:58.600 --> 00:03:59.750
These are just some examples

00:03:59.750 --> 00:04:02.440
of how scientific
research benefits society.

00:04:02.440 --> 00:04:03.840
Now, if you'll excuse me,

00:04:03.840 --> 00:04:05.340
I'll be setting up an emergency kit

00:04:05.340 --> 00:04:07.640
for the next time I lose
power during a storm.


Galaxies and gravity

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Language: en

00:00:00.370 --> 00:00:01.660
- [Instructor] Hello, everyone.

00:00:01.660 --> 00:00:05.700
Today, we're going to be talking
about galaxies and gravity.

00:00:05.700 --> 00:00:07.230
We know the Earth is a planet

00:00:07.230 --> 00:00:09.150
that is in orbit around the sun.

00:00:09.150 --> 00:00:11.900
This is called the heliocentric model.

00:00:11.900 --> 00:00:14.760
And the solar system is
an enormous space for us,

00:00:14.760 --> 00:00:16.700
encompassing every place that humans

00:00:16.700 --> 00:00:18.830
or our robots have ever been.

00:00:18.830 --> 00:00:22.000
But it's actually quite
small, cosmically speaking.

00:00:22.000 --> 00:00:24.510
Even our furthest spacecraft, Voyager 1,

00:00:24.510 --> 00:00:27.690
has only traveled less
than 0.1% of the distance

00:00:27.690 --> 00:00:29.380
to the nearest star.

00:00:29.380 --> 00:00:31.810
Our solar system is just a small component

00:00:31.810 --> 00:00:34.903
of a much, much larger set of structures.

00:00:35.950 --> 00:00:39.410
The sun is just one star
of hundreds of billions

00:00:39.410 --> 00:00:42.660
of stars in our galaxy, which
is called the Milky Way.

00:00:42.660 --> 00:00:46.730
And our galaxy is one of several
dozen in our galaxy group,

00:00:46.730 --> 00:00:48.730
which is called the Local Group.

00:00:48.730 --> 00:00:51.030
Other galaxies might belong
to larger collections

00:00:51.030 --> 00:00:53.810
that are called galaxy clusters.

00:00:53.810 --> 00:00:56.410
Now the same thing that
holds Earth in its orbit

00:00:56.410 --> 00:00:58.730
around the sun is what holds together

00:00:58.730 --> 00:01:02.783
massive groups and clusters
of galaxies: gravity.

00:01:04.080 --> 00:01:06.880
This is the same as the
gravity that makes a ball

00:01:06.880 --> 00:01:10.710
fall back to the ground when
you toss it up into the air.

00:01:10.710 --> 00:01:12.530
Gravity is a force that operates

00:01:12.530 --> 00:01:14.600
between two objects that have mass

00:01:14.600 --> 00:01:17.040
and tries to pull them closer together,

00:01:17.040 --> 00:01:19.700
whether those objects
are a ball and the Earth

00:01:19.700 --> 00:01:21.283
or two galaxies.

00:01:22.540 --> 00:01:26.100
Now the strength of this
pull depends on two things.

00:01:26.100 --> 00:01:29.040
First is the mass of both objects.

00:01:29.040 --> 00:01:31.400
So as either object gets more massive,

00:01:31.400 --> 00:01:33.520
the strength of gravity increases.

00:01:33.520 --> 00:01:36.250
For example, you have a
lot more mass than a ball.

00:01:36.250 --> 00:01:38.410
So the force of gravity
between you and the Earth

00:01:38.410 --> 00:01:40.500
is pulling harder than
the force of gravity

00:01:40.500 --> 00:01:41.930
between a ball and the Earth,

00:01:41.930 --> 00:01:43.900
and that's why it's a lot harder

00:01:43.900 --> 00:01:46.023
to throw you into the air than a ball.

00:01:47.160 --> 00:01:49.230
Gravity also depends on the distance

00:01:49.230 --> 00:01:51.740
between the centers of the objects.

00:01:51.740 --> 00:01:53.960
As the objects get farther apart,

00:01:53.960 --> 00:01:56.700
the strength of gravity decreases.

00:01:56.700 --> 00:01:59.980
For example, if there is a
ball on top of Mount Everest,

00:01:59.980 --> 00:02:03.400
the pull of Earth's gravity on
it is actually slightly less

00:02:03.400 --> 00:02:06.640
than the pull of gravity on
that same ball at sea level,

00:02:06.640 --> 00:02:09.030
because the top of the
mountain is farther away

00:02:09.030 --> 00:02:10.880
from the center of the Earth.

00:02:10.880 --> 00:02:13.170
Now, this is a very small effect,

00:02:13.170 --> 00:02:14.800
less than a percent difference,

00:02:14.800 --> 00:02:17.460
because the difference between
sea level and mountaintop

00:02:17.460 --> 00:02:19.690
is still very small
compared to the distance

00:02:19.690 --> 00:02:21.360
to the center of the Earth.

00:02:21.360 --> 00:02:22.820
But that's just on Earth.

00:02:22.820 --> 00:02:25.940
We know that things in
space are really far apart.

00:02:25.940 --> 00:02:28.600
The Earth is almost 93 million miles,

00:02:28.600 --> 00:02:31.740
that's 150 million
kilometers, from the sun.

00:02:31.740 --> 00:02:35.150
So if gravity is weaker when
objects are farther apart,

00:02:35.150 --> 00:02:37.600
then in order for gravity to
be keeping these structures

00:02:37.600 --> 00:02:41.930
bound together, they must be
really massive, and they are.

00:02:41.930 --> 00:02:45.270
The sun has a mass of about
two nonillion kilograms.

00:02:45.270 --> 00:02:48.000
That's 10 to the power of 30.

00:02:48.000 --> 00:02:49.730
And the Milky Way galaxy,

00:02:49.730 --> 00:02:52.930
which is about a quintillion
kilometers in diameter,

00:02:52.930 --> 00:02:57.463
has a mass of about 1.5
trillion times that of the sun.

00:02:58.590 --> 00:03:00.520
So thanks to their high masses,

00:03:00.520 --> 00:03:03.580
objects like our Milky Way
galaxy and our nearest neighbor,

00:03:03.580 --> 00:03:06.980
the Andromeda galaxy, which
are the two largest galaxies

00:03:06.980 --> 00:03:10.020
in the local group, can be
pulled together by gravity,

00:03:10.020 --> 00:03:12.730
even across millions of light years.

00:03:12.730 --> 00:03:15.900
In fact, gravity between our
two galaxies is so strong

00:03:15.900 --> 00:03:17.670
that it's actually pulling the Milky Way

00:03:17.670 --> 00:03:22.330
and Andromeda galaxies together
into an eventual collision.

00:03:22.330 --> 00:03:23.440
But eventually in this case

00:03:23.440 --> 00:03:26.683
means almost 5 billion years
from now, so no need to worry.

00:03:28.110 --> 00:03:30.410
To review, in this video
we covered how the Earth

00:03:30.410 --> 00:03:31.790
is part of the solar system

00:03:31.790 --> 00:03:34.210
and our solar system is part of a galaxy,

00:03:34.210 --> 00:03:36.640
and our galaxy is part of a group.

00:03:36.640 --> 00:03:39.450
Galaxy groups, galaxies and solar systems

00:03:39.450 --> 00:03:43.960
are all bound together by the
same force, that of gravity.

00:03:43.960 --> 00:03:46.130
Gravity is a force which
tries to pull objects

00:03:46.130 --> 00:03:48.600
with mass closer together and it is weaker

00:03:48.600 --> 00:03:50.870
for less massive objects or for objects

00:03:50.870 --> 00:03:52.300
that are farther apart.

00:03:52.300 --> 00:03:53.133
Thanks for watching

00:03:53.133 --> 00:03:55.490
and I hope you learned a
little bit of something.


Regional climates

WEBVTT
Kind: captions
Language: en

00:00:00.000 --> 00:00:01.360
- [Narrator] What's the
weather usually like

00:00:01.360 --> 00:00:03.100
in the winter where you live?

00:00:03.100 --> 00:00:05.590
If you asked someone in Fairbanks, Alaska

00:00:05.590 --> 00:00:07.500
they might describe below freezing days

00:00:07.500 --> 00:00:10.320
and navigating through
huge drifts of snow.

00:00:10.320 --> 00:00:12.540
If you asked someone
else in Miami, Florida

00:00:12.540 --> 00:00:14.060
they might tell you that most days

00:00:14.060 --> 00:00:16.150
it was warm enough to go to the beach.

00:00:16.150 --> 00:00:19.700
How can two places on the same
continent be so different?

00:00:19.700 --> 00:00:22.230
Well, it all comes down
to regional climates.

00:00:22.230 --> 00:00:24.010
Climate is the long term pattern

00:00:24.010 --> 00:00:25.640
of weather in a particular region.

00:00:25.640 --> 00:00:28.100
You can think of it as
the average weather.

00:00:28.100 --> 00:00:30.200
A region's climate
depends on many factors,

00:00:30.200 --> 00:00:32.370
including its latitude, elevation,

00:00:32.370 --> 00:00:34.040
and surrounding geographic features,

00:00:34.040 --> 00:00:36.429
such as oceans or mountains.

00:00:36.429 --> 00:00:38.570
Let's look at how regional climates depend

00:00:38.570 --> 00:00:40.240
on latitude first.

00:00:40.240 --> 00:00:42.380
Latitude refers to imaginary lines

00:00:42.380 --> 00:00:44.140
that measure how far north or south

00:00:44.140 --> 00:00:45.660
a place is from the Equator,

00:00:45.660 --> 00:00:47.770
which equally divides the earth in half.

00:00:47.770 --> 00:00:50.480
The Equator is marked
at zero degrees latitude

00:00:50.480 --> 00:00:53.100
and the mid-latitudes
increase north or south until

00:00:53.100 --> 00:00:54.190
they reach the poles,

00:00:54.190 --> 00:00:57.780
which are marked at 90 degrees
north and 90 degrees south.

00:00:57.780 --> 00:00:59.850
The sun heats the planet unevenly.

00:00:59.850 --> 00:01:01.810
So places at higher latitudes,

00:01:01.810 --> 00:01:03.610
which are farther from the Equator,

00:01:03.610 --> 00:01:06.720
get less direct sunlight
and solar energy on average,

00:01:06.720 --> 00:01:09.710
resulting in lower average
annual temperatures.

00:01:09.710 --> 00:01:12.720
Places at lower latitudes,
being closer to the Equator,

00:01:12.720 --> 00:01:15.750
get more direct sunlight
and solar energy on average,

00:01:15.750 --> 00:01:18.670
which results in higher
average annual temperatures.

00:01:18.670 --> 00:01:20.520
This uneven heating creates a pattern

00:01:20.520 --> 00:01:22.450
of low and high air pressure bands

00:01:22.450 --> 00:01:24.040
from the Equator to the poles,

00:01:24.040 --> 00:01:25.560
affecting the amount of precipitation

00:01:25.560 --> 00:01:27.540
that the different latitudes receive.

00:01:27.540 --> 00:01:29.480
In bands where moist air is rising,

00:01:29.480 --> 00:01:31.000
mainly at zero degrees latitude

00:01:31.000 --> 00:01:32.820
and 60 degrees north and south,

00:01:32.820 --> 00:01:34.680
places experience a lot of rainfall,

00:01:34.680 --> 00:01:36.310
especially around the Equator.

00:01:36.310 --> 00:01:38.240
And bands where dry air is sinking,

00:01:38.240 --> 00:01:40.780
like at the poles and 30
degrees north and south,

00:01:40.780 --> 00:01:43.180
places experience very little rainfall.

00:01:43.180 --> 00:01:45.660
This creates dry conditions
at the cold poles

00:01:45.660 --> 00:01:47.540
and desert conditions in regions

00:01:47.540 --> 00:01:50.310
near the 30 degree latitude lines.

00:01:50.310 --> 00:01:51.480
Another important influence

00:01:51.480 --> 00:01:53.510
on regional climates is elevation

00:01:53.510 --> 00:01:56.420
or how high a place is above sea level.

00:01:56.420 --> 00:01:58.920
As air rises from lower
to higher elevations,

00:01:58.920 --> 00:02:00.920
it expands and cools.

00:02:00.920 --> 00:02:03.690
That's why regions at higher
elevations, like mountains,

00:02:03.690 --> 00:02:05.760
tend to have lower
average air temperatures

00:02:05.760 --> 00:02:08.510
than regions at lower elevations.

00:02:08.510 --> 00:02:10.130
Speaking of mountains and seas,

00:02:10.130 --> 00:02:11.660
the presence of geographic features

00:02:11.660 --> 00:02:14.060
can also influence a region's climate.

00:02:14.060 --> 00:02:16.730
Let's start by diving into
the impact of water first.

00:02:16.730 --> 00:02:18.570
Water heats and cools slowly

00:02:18.570 --> 00:02:20.780
while land heats and cools quickly.

00:02:20.780 --> 00:02:23.960
As a result, temperature
variations tend to be much smaller

00:02:23.960 --> 00:02:25.710
for cities near large bodies of water

00:02:25.710 --> 00:02:27.940
than for cities surrounded by land.

00:02:27.940 --> 00:02:30.380
For example, let's compare
the yearly temperature ranges

00:02:30.380 --> 00:02:33.410
for Vancouver, which is close
to Canada's Pacific Coast

00:02:33.410 --> 00:02:35.650
and Winnipeg, which is further East

00:02:35.650 --> 00:02:37.430
in the interior of the country.

00:02:37.430 --> 00:02:40.050
This line graph follows the
average temperature in Celsius

00:02:40.050 --> 00:02:42.740
for each city throughout
the months of the year.

00:02:42.740 --> 00:02:45.380
Vancouver starts at
the year mildly chilly.

00:02:45.380 --> 00:02:47.760
Temperatures rise a bit
for a warmer summer.

00:02:47.760 --> 00:02:50.160
And then slope gradually back down.

00:02:50.160 --> 00:02:52.270
Overall, the city sees
a pretty small range

00:02:52.270 --> 00:02:53.750
of temperatures throughout the year

00:02:53.750 --> 00:02:56.270
because the nearby ocean
influences the local climate

00:02:56.270 --> 00:02:58.210
as it gradually warms and cools.

00:02:58.210 --> 00:03:01.830
Compared to Vancouver, Winnipeg
has a much colder winter

00:03:01.830 --> 00:03:03.820
and a slightly hotter summer resulting

00:03:03.820 --> 00:03:05.440
in a more dramatic range of temperatures

00:03:05.440 --> 00:03:06.580
throughout the year.

00:03:06.580 --> 00:03:09.240
We call a climate like
Vancouver's a Marine Climate

00:03:09.240 --> 00:03:12.013
and a climate like Winnipeg's
a Continental Climate.

00:03:13.030 --> 00:03:15.150
Things get pretty interesting
when we combine the impact

00:03:15.150 --> 00:03:16.700
of water with land forms.

00:03:16.700 --> 00:03:18.620
One unique example is a rain shadow,

00:03:18.620 --> 00:03:20.260
which can be found in
places where mountains

00:03:20.260 --> 00:03:22.300
are relatively close to the ocean.

00:03:22.300 --> 00:03:23.950
For example, here's a satellite image

00:03:23.950 --> 00:03:26.280
of the Andes Mountain
Range in south America.

00:03:26.280 --> 00:03:28.320
The mountains run north
to south in this image

00:03:28.320 --> 00:03:30.190
and they're close to the Pacific Ocean.

00:03:30.190 --> 00:03:31.890
Notice how the area between the Pacific

00:03:31.890 --> 00:03:33.470
and the Andes is green and lush,

00:03:33.470 --> 00:03:36.320
but the area behind the
Andes is brown and dry.

00:03:36.320 --> 00:03:38.050
That's the rain shadow.

00:03:38.050 --> 00:03:40.650
What causes such a huge change?

00:03:40.650 --> 00:03:42.870
Well, when warm moisture rich air

00:03:42.870 --> 00:03:45.840
from the ocean meets the
mountain it's forced upward.

00:03:45.840 --> 00:03:49.230
As it rises the air expands
and cools causing the moisture

00:03:49.230 --> 00:03:51.760
to condense and fall as precipitation.

00:03:51.760 --> 00:03:53.220
Now, the air is much drier,

00:03:53.220 --> 00:03:56.030
which allows it to change
temperature much faster.

00:03:56.030 --> 00:03:58.240
As that dry air descends
down the other side

00:03:58.240 --> 00:04:00.890
of the mountain it compresses
and quickly becomes warmer,

00:04:00.890 --> 00:04:03.270
which leads to increased evaporation.

00:04:03.270 --> 00:04:05.650
Overall, this results in
a cool and wet climate

00:04:05.650 --> 00:04:07.210
on the ocean side of the mountain

00:04:07.210 --> 00:04:10.030
and a warm and dry climate
inside the rain shadow,

00:04:10.030 --> 00:04:12.850
which is what we saw
on the satellite view.

00:04:12.850 --> 00:04:15.700
As you can see, regional climates
can get pretty complicated

00:04:15.700 --> 00:04:17.100
when you consider all of the factors

00:04:17.100 --> 00:04:18.600
that can go into them.

00:04:18.600 --> 00:04:20.260
Depending on the exact region,

00:04:20.260 --> 00:04:22.070
one factor may be more responsible

00:04:22.070 --> 00:04:23.930
for the local climate than the others.

00:04:23.930 --> 00:04:26.320
Like how the presence of the
Andes Mountains contributes

00:04:26.320 --> 00:04:28.650
to the rain shadow climate beyond them.

00:04:28.650 --> 00:04:30.610
Let's look back at our
two very different cities

00:04:30.610 --> 00:04:33.200
from before so we can see
how the factors we discussed

00:04:33.200 --> 00:04:34.690
affect their winter climates.

00:04:34.690 --> 00:04:37.270
Fairbanks is at a very
high northern latitude

00:04:37.270 --> 00:04:40.310
which helps explain why it's
so freezing in the winter.

00:04:40.310 --> 00:04:43.640
Miami is much closer to the
Equator and near an ocean,

00:04:43.640 --> 00:04:46.690
so it experiences a very
warm and mild winter.

00:04:46.690 --> 00:04:49.360
Which of these cities would you
like to visit in the winter?

00:04:49.360 --> 00:04:51.720
Whether you prefer hanging
out on sunny shorelines

00:04:51.720 --> 00:04:54.010
or exploring frosty winter wonderlands,

00:04:54.010 --> 00:04:55.390
there's a regional climate somewhere

00:04:55.390 --> 00:04:57.253
in the world that you'd probably enjoy.


Plate tectonics and the ocean floor

WEBVTT
Kind: captions
Language: en

00:00:00.200 --> 00:00:02.300
- [Instructor] Imagine
that all the Earth's oceans

00:00:02.300 --> 00:00:03.890
disappeared for a day.

00:00:03.890 --> 00:00:07.450
And imagine that you being the
excellent Explorer you are,

00:00:07.450 --> 00:00:09.730
decided to go investigate.

00:00:09.730 --> 00:00:12.350
You'd travel across the continental shelf,

00:00:12.350 --> 00:00:16.200
down the continental slope
and across the abyssal plain.

00:00:16.200 --> 00:00:18.950
You'd see gaping trenches
running deep into the ground,

00:00:18.950 --> 00:00:22.220
and mountains taller than any
mountain on the continents.

00:00:22.220 --> 00:00:23.740
And you might wonder,

00:00:23.740 --> 00:00:27.690
what causes such dramatic
landscapes to be formed?

00:00:27.690 --> 00:00:30.560
Earth's lithosphere, which
is made up of the crust

00:00:30.560 --> 00:00:32.680
and the upper part of
the mantle, is broken up

00:00:32.680 --> 00:00:36.520
into large puzzle piece like
chunks called tectonic plates.

00:00:36.520 --> 00:00:38.830
These tectonic plates move around slowly

00:00:38.830 --> 00:00:41.500
over millions of years on
the section of the mantle

00:00:41.500 --> 00:00:44.583
below the lithosphere, which
we call the asthenosphere.

00:00:45.600 --> 00:00:47.850
There are two types of tectonic plates,

00:00:47.850 --> 00:00:50.540
oceanic plates and continental plates.

00:00:50.540 --> 00:00:53.500
The continental plates,
as you probably guessed,

00:00:53.500 --> 00:00:55.460
are the ones that make up the continents.

00:00:55.460 --> 00:00:58.980
The oceanic plates are the ones
that make up the sea floor.

00:00:58.980 --> 00:01:01.130
The main difference between oceanic plates

00:01:01.130 --> 00:01:03.560
and continental plates
is the type of crust

00:01:03.560 --> 00:01:05.070
found on each plate.

00:01:05.070 --> 00:01:07.100
Oceanic crust and continental crust

00:01:07.100 --> 00:01:09.010
are made out of different kinds of rock.

00:01:09.010 --> 00:01:11.750
The continental crust
contains a lot of granite,

00:01:11.750 --> 00:01:13.630
which is an igneous rock.

00:01:13.630 --> 00:01:15.250
This means that it was made out of rock

00:01:15.250 --> 00:01:16.700
that was once molten.

00:01:16.700 --> 00:01:19.140
The oceanic crust has
a lot of basalt in it,

00:01:19.140 --> 00:01:21.440
which is another kind of igneous rock.

00:01:21.440 --> 00:01:22.970
The difference in the kinds of rock

00:01:22.970 --> 00:01:26.210
that the crusts are made out
of means that the oceanic crust

00:01:26.210 --> 00:01:28.460
is denser than the continental crust.

00:01:28.460 --> 00:01:30.420
If you took a cubic centimeter of the rock

00:01:30.420 --> 00:01:34.190
from the continental crust,
it would be about 2.7 grams.

00:01:34.190 --> 00:01:36.440
A cubic centimeter from the oceanic crust,

00:01:36.440 --> 00:01:39.510
on the other hand, would
weigh about three grams.

00:01:39.510 --> 00:01:42.750
While this difference in density
might not seem like much,

00:01:42.750 --> 00:01:46.020
it completely changes how
tectonic plates interact.

00:01:46.020 --> 00:01:47.970
The high density of oceanic crust

00:01:47.970 --> 00:01:50.830
causes oceanic plates to
sink into the asthenosphere

00:01:50.830 --> 00:01:53.220
a bit more than continental plates do.

00:01:53.220 --> 00:01:55.470
When an oceanic plate
collides with another plate

00:01:55.470 --> 00:01:59.150
at a convergent boundary,
it always follows this rule,

00:01:59.150 --> 00:02:03.420
the denser plates always dives
beneath the less dense plate.

00:02:03.420 --> 00:02:04.810
When it's an oceanic plates

00:02:04.810 --> 00:02:06.980
and a continental plate converging,

00:02:06.980 --> 00:02:10.370
the denser oceanic plates
is the one that dips down.

00:02:10.370 --> 00:02:13.230
And when it's two oceanic
plates that are colliding,

00:02:13.230 --> 00:02:16.140
the older, denser oceanic
plate will move under

00:02:16.140 --> 00:02:19.080
the newer and less dense oceanic plates.

00:02:19.080 --> 00:02:21.000
And over time, the denser plate

00:02:21.000 --> 00:02:23.270
will be recycled into asthenosphere.

00:02:23.270 --> 00:02:24.750
The place where the plates collide

00:02:24.750 --> 00:02:26.410
is called a subduction zone.

00:02:26.410 --> 00:02:28.200
This bending of the denser plates

00:02:28.200 --> 00:02:30.530
under the other creates a trench.

00:02:30.530 --> 00:02:33.030
The deepest one is the Mariana Trench,

00:02:33.030 --> 00:02:35.180
which is located where the Pacific plates

00:02:35.180 --> 00:02:37.410
dives under the Marianna plates.

00:02:37.410 --> 00:02:40.620
The trench is about 11 kilometers deep.

00:02:40.620 --> 00:02:42.790
The plate that sinks into asthenosphere

00:02:42.790 --> 00:02:45.440
often has some water and
fluids trapped inside of it.

00:02:45.440 --> 00:02:48.500
These fluids heat up and
bubble to the surface.

00:02:48.500 --> 00:02:50.710
The hot fluids can cause
sections of mantle rock

00:02:50.710 --> 00:02:53.280
to melt into magma, which then rises

00:02:53.280 --> 00:02:56.030
to the surface and creates volcanoes.

00:02:56.030 --> 00:02:58.570
And you might be wondering,
if the sea floor is constantly

00:02:58.570 --> 00:03:01.960
being destroyed then what
keeps the earth from shrinking?

00:03:01.960 --> 00:03:05.400
Well, new sea floor is
constantly being created too.

00:03:05.400 --> 00:03:07.780
This happens when two
tectonic plates move away

00:03:07.780 --> 00:03:10.260
from each other at a divergent boundary.

00:03:10.260 --> 00:03:12.920
When two plates diverge
in the middle of an ocean,

00:03:12.920 --> 00:03:15.220
it creates a kind of
underwater mountain range

00:03:15.220 --> 00:03:17.450
called a mid-ocean ridge.

00:03:17.450 --> 00:03:20.570
As the plates move apart
at mid-ocean ridges,

00:03:20.570 --> 00:03:25.570
magma moves up, cools and forms
a new younger lithosphere.

00:03:26.000 --> 00:03:27.080
You can think of this process

00:03:27.080 --> 00:03:29.380
like a really slow conveyor belt.

00:03:29.380 --> 00:03:31.630
New ocean sea floor is made at the ridges,

00:03:31.630 --> 00:03:34.560
and moves away from them
over millions of years.

00:03:34.560 --> 00:03:35.960
This means that the oceanic crust

00:03:35.960 --> 00:03:38.450
that is closest to the
ridge is the youngest.

00:03:38.450 --> 00:03:39.950
And as it moves away from the ridge,

00:03:39.950 --> 00:03:42.190
the crust gets older and older.

00:03:42.190 --> 00:03:45.440
As it ages, the crust becomes
cooler and more dense.

00:03:45.440 --> 00:03:46.930
And eventually it dips back down

00:03:46.930 --> 00:03:49.540
into the asthenosphere at the trenches.

00:03:49.540 --> 00:03:51.600
The sea floor is perhaps the most

00:03:51.600 --> 00:03:53.370
unexplored part of our planet.

00:03:53.370 --> 00:03:56.250
So if they do drain the
ocean and you go for a walk

00:03:56.250 --> 00:03:58.610
at the bottom of the sea,
I hope you'll tell us all

00:03:58.610 --> 00:03:59.910
what it's like down there.


Introduction to plate tectonics

WEBVTT
Kind: captions
Language: en

00:00:00.000 --> 00:00:01.230
- [Narrator] What if I told you

00:00:01.230 --> 00:00:03.890
that the earth below you is moving?

00:00:03.890 --> 00:00:06.930
You'd probably say,
"Of course it's moving.

00:00:06.930 --> 00:00:08.120
We're standing on a planet

00:00:08.120 --> 00:00:09.900
that's spinning on its axis

00:00:09.900 --> 00:00:11.570
while revolving around the Sun

00:00:11.570 --> 00:00:14.570
at about 107,000 kilometers per hour.

00:00:14.570 --> 00:00:15.890
And on top of that,

00:00:15.890 --> 00:00:18.300
our whole solar system
is circling the center

00:00:18.300 --> 00:00:19.960
of the Milky Way galaxy."

00:00:19.960 --> 00:00:22.490
But there's another kind of
movement that happens slowly

00:00:22.490 --> 00:00:24.660
in the rock beneath your feet.

00:00:24.660 --> 00:00:27.730
Earth's lithosphere, which
is made up of the crust

00:00:27.730 --> 00:00:29.320
and the upper part of the mantle,

00:00:29.320 --> 00:00:32.570
is broken up into pieces
called tectonic plates.

00:00:32.570 --> 00:00:35.590
These plates move around on
top of the asthenosphere,

00:00:35.590 --> 00:00:36.920
which is the section of the mantle

00:00:36.920 --> 00:00:38.660
just below the lithosphere.

00:00:38.660 --> 00:00:40.810
Don't bother racing a tectonic plate,

00:00:40.810 --> 00:00:43.460
because your victory would be guaranteed.

00:00:43.460 --> 00:00:45.580
Tectonic plates typically only move

00:00:45.580 --> 00:00:47.060
a few centimeters in a year,

00:00:47.060 --> 00:00:49.960
which is about as fast
as your fingernails grow.

00:00:49.960 --> 00:00:54.520
However, after millions of
years, those distances add up.

00:00:54.520 --> 00:00:56.430
This means that the Earth hasn't always

00:00:56.430 --> 00:00:58.060
looked the way it does now.

00:00:58.060 --> 00:01:00.210
Scientists believe that
the continents were once

00:01:00.210 --> 00:01:04.150
all connected in one big
supercontinent called Pangea.

00:01:04.150 --> 00:01:07.410
Just imagine if the continents
were still connected today.

00:01:07.410 --> 00:01:09.770
You could drive from Africa to Antarctica

00:01:09.770 --> 00:01:12.660
or even take a train from
South America to Europe.

00:01:12.660 --> 00:01:16.580
Over 200 million years,
Pangea broke apart,

00:01:16.580 --> 00:01:19.760
and the pieces drifted into
the continents we know today.

00:01:19.760 --> 00:01:22.630
So if the plates move so slowly,

00:01:22.630 --> 00:01:24.530
how do we know that they move at all?

00:01:24.530 --> 00:01:26.440
Scientists have documented evidence

00:01:26.440 --> 00:01:27.950
from various features on Earth

00:01:27.950 --> 00:01:30.500
that support the theory
of plate tectonics.

00:01:30.500 --> 00:01:32.830
If you cut out the continents
on a map, you could see

00:01:32.830 --> 00:01:35.140
that they almost fit together
like a jigsaw puzzle.

00:01:35.140 --> 00:01:38.240
For example, the east coast
of South America looks

00:01:38.240 --> 00:01:40.680
like it could fit into
the west coast of Africa.

00:01:40.680 --> 00:01:42.930
Matching or complementary coastlines

00:01:42.930 --> 00:01:44.030
is one piece of evidence

00:01:44.030 --> 00:01:46.840
that continents were once
in different locations.

00:01:46.840 --> 00:01:48.120
Another piece of evidence

00:01:48.120 --> 00:01:49.810
is that scientists have found fossils

00:01:49.810 --> 00:01:52.770
from the same species
on different continents.

00:01:52.770 --> 00:01:54.610
There's no way those land organisms

00:01:54.610 --> 00:01:56.520
could've traveled across the ocean.

00:01:56.520 --> 00:01:58.220
This suggests that the animals lived

00:01:58.220 --> 00:02:00.140
when the continents were connected.

00:02:00.140 --> 00:02:02.100
And the plates are still moving,

00:02:02.100 --> 00:02:04.530
slowly but surely, to this day.

00:02:04.530 --> 00:02:07.490
But they aren't all moving
in the same direction.

00:02:07.490 --> 00:02:09.450
A plate can collide with one plate,

00:02:09.450 --> 00:02:12.940
move away from a different
plate, and slide past another.

00:02:12.940 --> 00:02:15.700
We categorize the ways plates
interact at their edges

00:02:15.700 --> 00:02:20.080
as having convergent, divergent,
or transform boundaries.

00:02:20.080 --> 00:02:22.370
Con is a Latin prefix meaning together,

00:02:22.370 --> 00:02:24.710
so convergent plate boundaries are places

00:02:24.710 --> 00:02:26.690
where two plates come together.

00:02:26.690 --> 00:02:29.590
Let's take a look at an example
of a convergent boundary

00:02:29.590 --> 00:02:31.610
where the Indian tectonic plate collides

00:02:31.610 --> 00:02:33.360
with the Eurasian plate.

00:02:33.360 --> 00:02:35.800
The crust of the plate becomes compressed,

00:02:35.800 --> 00:02:38.570
and the Indian tectonic
plate gradually moves

00:02:38.570 --> 00:02:40.450
under the Eurasian plate.

00:02:40.450 --> 00:02:42.500
However, the lower density of the crust

00:02:42.500 --> 00:02:44.520
keeps the Indian plate from sinking back

00:02:44.520 --> 00:02:46.570
into the asthenosphere all the way.

00:02:46.570 --> 00:02:48.490
This lifts up the Eurasian plate

00:02:48.490 --> 00:02:50.540
and creates the Himalayan mountains.

00:02:50.540 --> 00:02:53.530
These mountains are some of
the highest in the world,

00:02:53.530 --> 00:02:55.280
and they include Mount Everest,

00:02:55.280 --> 00:02:57.940
which is the tallest
mountain above sea level.

00:02:57.940 --> 00:03:00.580
And the two plates are still colliding.

00:03:00.580 --> 00:03:02.270
This causes the Himalayas to grow

00:03:02.270 --> 00:03:04.710
by more than one centimeter each year.

00:03:04.710 --> 00:03:06.070
Another kind of plate movement

00:03:06.070 --> 00:03:08.230
is called a divergent boundary.

00:03:08.230 --> 00:03:09.740
The di in divergent comes

00:03:09.740 --> 00:03:11.710
from a Latin prefix meaning apart,

00:03:11.710 --> 00:03:13.380
so divergent boundaries happen

00:03:13.380 --> 00:03:15.780
where two tectonic plates move apart.

00:03:15.780 --> 00:03:17.850
Divergent boundaries can
create different kinds

00:03:17.850 --> 00:03:21.723
of land forms, like rift
valleys and mid-ocean ridges.

00:03:22.630 --> 00:03:24.030
The third kind of plate boundary

00:03:24.030 --> 00:03:27.340
is called a transform
boundary or transform fault,

00:03:27.340 --> 00:03:30.640
and it happens when two
plates slide past each other.

00:03:30.640 --> 00:03:33.160
Okay, maybe slide isn't
the best word for it,

00:03:33.160 --> 00:03:36.410
because the plates don't move
in one continuous motion.

00:03:36.410 --> 00:03:38.840
You can imagine when two incredibly large,

00:03:38.840 --> 00:03:41.190
bulky, rocky things move past each other,

00:03:41.190 --> 00:03:43.080
there's a lot of friction.

00:03:43.080 --> 00:03:45.250
Pressure builds up between the plates,

00:03:45.250 --> 00:03:47.140
and once it gets to be too much,

00:03:47.140 --> 00:03:49.870
the plates slip and release the pressure.

00:03:49.870 --> 00:03:52.150
This motion causes earthquakes.

00:03:52.150 --> 00:03:55.330
And you might be wondering,
what causes plates to move?

00:03:55.330 --> 00:03:57.870
Well, scientists are always
learning about the Earth,

00:03:57.870 --> 00:04:00.010
since the Earth is so complex.

00:04:00.010 --> 00:04:03.000
Although Earth's internal
heat may play a small role,

00:04:03.000 --> 00:04:05.870
more evidence shows that gravity is key.

00:04:05.870 --> 00:04:07.470
Tectonic plates are solid,

00:04:07.470 --> 00:04:10.300
and they're denser and cooler
than the asthenosphere.

00:04:10.300 --> 00:04:13.030
Because the asthenosphere
is also pretty solid,

00:04:13.030 --> 00:04:14.800
the plates rest on top of it.

00:04:14.800 --> 00:04:17.170
However, the asthenosphere is so hot

00:04:17.170 --> 00:04:18.980
that it can behave a bit like clay.

00:04:18.980 --> 00:04:21.170
This means that at convergent boundaries,

00:04:21.170 --> 00:04:24.220
the edges of the plates can
sink into the asthenosphere,

00:04:24.220 --> 00:04:27.140
a process that is driven by gravity.

00:04:27.140 --> 00:04:30.290
So even though you'd win in a
race against a tectonic plate,

00:04:30.290 --> 00:04:33.110
the plate will still keep
on moving millions of years

00:04:33.110 --> 00:04:35.423
after you've declared
yourself to be the winner.


The solar system

WEBVTT
Kind: captions
Language: en

00:00:00.200 --> 00:00:04.390
- [Narrator] The Earth isn't
flat, but the solar system is.

00:00:04.390 --> 00:00:06.950
About 4.6 billion years ago,

00:00:06.950 --> 00:00:08.840
the material that makes
up our solar system

00:00:08.840 --> 00:00:10.500
was in the form of a nebula,

00:00:10.500 --> 00:00:14.470
which is pretty much a big
cloud of gas and dust in space.

00:00:14.470 --> 00:00:17.510
Gravity flattened this material
into a disc like this one

00:00:17.510 --> 00:00:19.800
and then pulled everything
towards the center.

00:00:19.800 --> 00:00:21.960
Eventually, the pressure became so great

00:00:21.960 --> 00:00:23.320
that the star was formed.

00:00:23.320 --> 00:00:25.190
The sun, the remaining dust

00:00:25.190 --> 00:00:27.230
and gas particles collided with each other

00:00:27.230 --> 00:00:30.050
and eventually formed
larger objects like Earth.

00:00:30.050 --> 00:00:32.650
Together, the sun and
all the objects in space

00:00:32.650 --> 00:00:35.680
that as gravity keeps an orbit,
make up our solar system.

00:00:35.680 --> 00:00:39.010
We call the biggest objects
that orbit the sun, planets.

00:00:39.010 --> 00:00:41.020
Our solar system has eight of them;

00:00:41.020 --> 00:00:44.760
Mercury, Venus, Earth, Mars, Jupiter,

00:00:44.760 --> 00:00:47.470
Saturn, Uranus, and Neptune.

00:00:47.470 --> 00:00:51.080
These eight planets are
divided by the asteroid belt.

00:00:51.080 --> 00:00:53.100
Asteroids are rocks that orbit the sun

00:00:53.100 --> 00:00:55.050
that are much smaller than planets

00:00:55.050 --> 00:00:57.210
and they're made up of nickel and iron.

00:00:57.210 --> 00:01:01.360
And unlike the planets,
most asteroids aren't round.

00:01:01.360 --> 00:01:03.570
Beyond Neptune is the Oort cloud,

00:01:03.570 --> 00:01:05.940
a space at the very
edge of the solar system

00:01:05.940 --> 00:01:09.110
that's filled with comets,
which are like space snowballs

00:01:09.110 --> 00:01:11.090
that are made up of ice and dust.

00:01:11.090 --> 00:01:13.150
Sometimes comets enter the inner part

00:01:13.150 --> 00:01:15.400
of our solar system and
can even be seen from Earth

00:01:15.400 --> 00:01:17.860
with long tails of ionized gases.

00:01:17.860 --> 00:01:19.520
One of the most famous comets

00:01:19.520 --> 00:01:20.730
is Halley's comet,

00:01:20.730 --> 00:01:24.010
which only comes near
Earth every 75 years or so.

00:01:24.010 --> 00:01:26.283
Be on the lookout for it in 2061.

00:01:27.200 --> 00:01:29.290
The four planets on the
side of the asteroid belt,

00:01:29.290 --> 00:01:31.640
closer to the sun, are called the inner

00:01:31.640 --> 00:01:33.320
or terrestrial planets.

00:01:33.320 --> 00:01:36.500
The word terrestrial comes
from the Latin word for Earth.

00:01:36.500 --> 00:01:39.520
Terrestrial planets have
solid, rocky surfaces,

00:01:39.520 --> 00:01:43.810
thin atmospheres, few or
no moons and no rings.

00:01:43.810 --> 00:01:45.190
The closest planet to the sun

00:01:45.190 --> 00:01:46.770
is called Mercury.

00:01:46.770 --> 00:01:49.150
It's the smallest planet
in the solar system

00:01:49.150 --> 00:01:51.420
and it doesn't have any moons.

00:01:51.420 --> 00:01:53.110
Next, there's Venus.

00:01:53.110 --> 00:01:54.950
It's the closest planet to Earth

00:01:54.950 --> 00:01:57.530
and like Mercury, it doesn't have a moon.

00:01:57.530 --> 00:02:00.530
Venus shines bright in
the sky, like a star.

00:02:00.530 --> 00:02:02.520
It's about the same size as Earth,

00:02:02.520 --> 00:02:04.610
but you wouldn't wanna live on it.

00:02:04.610 --> 00:02:06.950
It's the hottest planet
in the solar system

00:02:06.950 --> 00:02:09.180
and its atmosphere contains
an unbreathable mixture

00:02:09.180 --> 00:02:11.820
of carbon dioxide and sulfuric acid.

00:02:11.820 --> 00:02:14.340
Next is our home planet, Earth.

00:02:14.340 --> 00:02:17.220
Earth is the only planet
known to have life on it.

00:02:17.220 --> 00:02:20.570
The last terrestrial planet
in our solar system is Mars.

00:02:20.570 --> 00:02:23.750
Mars has a very thin
atmosphere of carbon dioxide

00:02:23.750 --> 00:02:25.570
and it has two moons.

00:02:25.570 --> 00:02:28.100
We've sent robots called rovers to Mars

00:02:28.100 --> 00:02:30.460
in order to explore the planet surface.

00:02:30.460 --> 00:02:32.610
The planets on the other
side of the asteroid belt

00:02:32.610 --> 00:02:34.460
are called the outer planets.

00:02:34.460 --> 00:02:37.460
And unlike the inner planets,
they're not made out of rock,

00:02:37.460 --> 00:02:40.000
instead, they're made
out of gases and liquids

00:02:40.000 --> 00:02:42.480
and they have many moons and rings

00:02:42.480 --> 00:02:44.210
and they're much, much colder

00:02:44.210 --> 00:02:47.100
and much, much bigger than
the terrestrial planets.

00:02:47.100 --> 00:02:49.570
For instance, the planet Jupiter is so big

00:02:49.570 --> 00:02:52.840
that it could fit about
1,300 Earths inside of it.

00:02:52.840 --> 00:02:55.290
We call Jupiter a gas giant, because,

00:02:55.290 --> 00:02:58.500
you guessed it, it's
giant and made up of gas.

00:02:58.500 --> 00:03:01.580
Its atmosphere is mostly made
up of hydrogen and helium.

00:03:01.580 --> 00:03:04.060
It has more than 50 moons.

00:03:04.060 --> 00:03:06.380
One of Jupiter's moons, Ganymede,

00:03:06.380 --> 00:03:09.320
is bigger by volume than
the planet Mercury is.

00:03:09.320 --> 00:03:12.060
Jupiter spins really fast on its axis.

00:03:12.060 --> 00:03:13.560
This means that a day on Jupiter

00:03:13.560 --> 00:03:16.030
is a little less than 10 hours long.

00:03:16.030 --> 00:03:18.470
If you travel another
650 million kilometers

00:03:18.470 --> 00:03:20.710
or so from Jupiter, you'd see Saturn,

00:03:20.710 --> 00:03:22.330
another gas giant.

00:03:22.330 --> 00:03:25.620
In 1610, Galileo Galilei
became the first person

00:03:25.620 --> 00:03:27.110
to see Saturn's rings.

00:03:27.110 --> 00:03:29.230
Because his telescope
wasn't strong enough,

00:03:29.230 --> 00:03:30.820
he couldn't tell what they were.

00:03:30.820 --> 00:03:33.440
He thought it looked
like the planet had ears.

00:03:33.440 --> 00:03:36.230
Even though Saturn's rings
look smooth from a distance,

00:03:36.230 --> 00:03:38.720
they're actually made out
of rocks and pieces of ice

00:03:38.720 --> 00:03:39.670
that orbit the planet

00:03:39.670 --> 00:03:42.020
because of Saturn's gravitational pull.

00:03:42.020 --> 00:03:44.000
The next planet is called Uranus.

00:03:44.000 --> 00:03:45.430
It's the sideways planet.

00:03:45.430 --> 00:03:47.810
Uranus has smaller rings than Saturn does

00:03:47.810 --> 00:03:49.540
and it's so far away from the Earth

00:03:49.540 --> 00:03:51.610
that we can only see it with a telescope.

00:03:51.610 --> 00:03:52.940
Even farther away from Earth,

00:03:52.940 --> 00:03:55.600
is the big and blue planet, Neptune.

00:03:55.600 --> 00:03:57.860
Because Neptune is so
far away from the sun,

00:03:57.860 --> 00:03:59.560
it's really cold here.

00:03:59.560 --> 00:04:00.900
The average temperature of Neptune

00:04:00.900 --> 00:04:04.070
is about negative 214 degree Celsius.

00:04:04.070 --> 00:04:06.680
It's also the windiest
planet in our solar system

00:04:06.680 --> 00:04:09.840
with winds going at more than
2000 kilometers per hour.

00:04:09.840 --> 00:04:12.140
So if you ever visit, bundle up.

00:04:12.140 --> 00:04:14.270
The planets don't all take
the same amount of time

00:04:14.270 --> 00:04:15.270
to orbit the sun.

00:04:15.270 --> 00:04:17.300
For example, it takes Jupiter 12 years

00:04:17.300 --> 00:04:19.420
to orbit the sun just once.

00:04:19.420 --> 00:04:20.620
And the same amount of time,

00:04:20.620 --> 00:04:23.810
Mercury has already orbited
the sun nearly 50 times

00:04:23.810 --> 00:04:26.480
and Neptune hasn't even
made it around once.

00:04:26.480 --> 00:04:28.190
Although humans have visited the moon,

00:04:28.190 --> 00:04:30.050
we haven't built a rocket
ship that can allow us

00:04:30.050 --> 00:04:31.750
to visit our neighboring planets yet.

00:04:31.750 --> 00:04:33.730
We've been able to learn
more about our solar system

00:04:33.730 --> 00:04:35.670
by using other kinds of technology.

00:04:35.670 --> 00:04:37.570
Humans have built incredible telescopes

00:04:37.570 --> 00:04:40.610
that allow us to see into
our solar system and beyond,

00:04:40.610 --> 00:04:42.620
and we've sent probes to other planets

00:04:42.620 --> 00:04:44.530
and captured stunning images.

00:04:44.530 --> 00:04:46.190
Even with all this research,

00:04:46.190 --> 00:04:48.150
scientists are still learning new things

00:04:48.150 --> 00:04:49.080
about our solar system

00:04:49.080 --> 00:04:51.160
and its place in the rest of the universe.

00:04:51.160 --> 00:04:53.590
So maybe one day you could help solve some

00:04:53.590 --> 00:04:55.690
of the solar system's great mysteries too.


Solar eclipses

WEBVTT
Kind: captions
Language: en

00:00:00.000 --> 00:00:01.900
- [Narrator] Have you ever
been minding your own business

00:00:01.900 --> 00:00:04.590
enjoying the sun when
someone steps in front of you

00:00:04.590 --> 00:00:06.350
and blocks your sunlight?

00:00:06.350 --> 00:00:09.200
This is pretty much what
happens during a solar eclipse

00:00:09.200 --> 00:00:11.430
except on a planetary scale.

00:00:11.430 --> 00:00:13.180
As earth revolves around the sun,

00:00:13.180 --> 00:00:15.300
the moon revolves around earth too.

00:00:15.300 --> 00:00:19.010
Once in a while, the sun, the
moon and earth all line up

00:00:19.010 --> 00:00:21.280
so that the moon shadow falls onto earth

00:00:21.280 --> 00:00:23.440
causing a solar eclipse.

00:00:23.440 --> 00:00:26.010
During a solar eclipse, the
moon blocks the sun's light

00:00:26.010 --> 00:00:28.070
and energy from reaching part of earth.

00:00:28.070 --> 00:00:30.800
So how does a solar
eclipse appear from earth?

00:00:30.800 --> 00:00:33.590
Well, if you're standing in the
center of the moon's shadow,

00:00:33.590 --> 00:00:34.620
you'd see the moon appear

00:00:34.620 --> 00:00:36.810
to completely cover the sun's disk.

00:00:36.810 --> 00:00:39.410
This is called a total solar eclipse.

00:00:39.410 --> 00:00:41.560
There are other types of solar eclipses

00:00:41.560 --> 00:00:42.560
but we're going to focus

00:00:42.560 --> 00:00:45.090
on total solar eclipses in this video.

00:00:45.090 --> 00:00:47.650
During a total solar
eclipse, the outermost layer

00:00:47.650 --> 00:00:51.120
of the sun's atmosphere
called its corona is visible.

00:00:51.120 --> 00:00:54.450
On a non-solar eclipse day,
the Corona is invisible to us

00:00:54.450 --> 00:00:56.190
because we can't see past the bright light

00:00:56.190 --> 00:00:57.480
from the sun's surface.

00:00:57.480 --> 00:00:59.560
Remember to never stare or look at the sun

00:00:59.560 --> 00:01:02.430
with your naked eye,
binoculars or a telescope.

00:01:02.430 --> 00:01:04.790
Looking even for a few
seconds can cause severe

00:01:04.790 --> 00:01:06.280
and permanent eye damage.

00:01:06.280 --> 00:01:08.840
Just because you can't look
directly at the sun doesn't mean

00:01:08.840 --> 00:01:10.930
that you can't enjoy watching
a solar eclipse, though.

00:01:10.930 --> 00:01:14.070
You can watch the eclipse in
action through a pinhole viewer

00:01:14.070 --> 00:01:16.930
or ultraviolet ray blocking
solar eclipse glasses.

00:01:16.930 --> 00:01:19.620
If you're in the moon shadow
during a total solar eclipse,

00:01:19.620 --> 00:01:22.440
you might also notice
a drop in temperature.

00:01:22.440 --> 00:01:25.950
On average, the temperature
drops about 5.5 degree Celsius

00:01:25.950 --> 00:01:27.510
during a total solar eclipse.

00:01:27.510 --> 00:01:29.430
This is because the
moon block solar energy

00:01:29.430 --> 00:01:31.000
from reaching earth.

00:01:31.000 --> 00:01:34.090
Total solar eclipses
last only a few minutes.

00:01:34.090 --> 00:01:37.470
This is because the moon is
always revolving around earth.

00:01:37.470 --> 00:01:40.480
As the moon keeps on moving,
the sun starts to reappear

00:01:40.480 --> 00:01:42.720
around the moon and
eventually the sun returns

00:01:42.720 --> 00:01:45.010
to its usual round and sunny self.

00:01:45.010 --> 00:01:46.270
But how is it even possible

00:01:46.270 --> 00:01:48.890
for the moon to appear to block
the sun in the first place?

00:01:48.890 --> 00:01:51.030
The sun and the moon aren't the same size.

00:01:51.030 --> 00:01:52.600
In fact, the sun is so big

00:01:52.600 --> 00:01:56.100
that 64.3 million moons
could fit inside of it.

00:01:56.100 --> 00:01:59.340
However, coincidentally,
the sun is far enough away

00:01:59.340 --> 00:02:01.530
that the moon and the sun
appear to us earthlings

00:02:01.530 --> 00:02:03.690
to be the same size in the sky.

00:02:03.690 --> 00:02:05.710
So when the moon moves
between the sun and earth

00:02:05.710 --> 00:02:07.100
during a total solar eclipse,

00:02:07.100 --> 00:02:08.020
it appears from earth

00:02:08.020 --> 00:02:11.070
to cover the disk of
the sun almost exactly.

00:02:11.070 --> 00:02:13.690
Total solar eclipses
like all solar eclipses

00:02:13.690 --> 00:02:16.410
happen only during a new
moon which is the only time

00:02:16.410 --> 00:02:18.140
in the moon's orbit
where the moon is located

00:02:18.140 --> 00:02:19.730
between the sun and earth.

00:02:19.730 --> 00:02:22.730
Solar eclipses don't happen
every new moon though.

00:02:22.730 --> 00:02:23.700
Most of the time,

00:02:23.700 --> 00:02:26.700
the moon, earth and the
sun are not lined up.

00:02:26.700 --> 00:02:28.610
This is because the
plane of the moon's orbit

00:02:28.610 --> 00:02:30.960
around earth is at a
different angle than the plane

00:02:30.960 --> 00:02:32.530
of Earth's orbit around the sun.

00:02:32.530 --> 00:02:34.750
This means that the moon's
shadow is usually too high

00:02:34.750 --> 00:02:37.290
or too low to hit earth
and cause an eclipse.

00:02:37.290 --> 00:02:39.440
Total solar eclipses won't
be visible from earth

00:02:39.440 --> 00:02:41.570
in about 600 million years.

00:02:41.570 --> 00:02:44.620
This is because the moon's orbit
is gradually getting bigger

00:02:44.620 --> 00:02:45.500
with the moon moving

00:02:45.500 --> 00:02:48.250
about four centimeters
away from earth each year.

00:02:48.250 --> 00:02:50.970
So one day the moon will
appear to be too small

00:02:50.970 --> 00:02:53.600
in the sky to entirely
block the sun's light.

00:02:53.600 --> 00:02:55.520
Total solar eclipses take place on earth

00:02:55.520 --> 00:02:57.020
every 18 months or so,

00:02:57.020 --> 00:02:59.030
but sometimes they're only
visible from the middle

00:02:59.030 --> 00:03:00.860
of an ocean or a desert.

00:03:00.860 --> 00:03:01.693
If you're curious

00:03:01.693 --> 00:03:03.740
about when the next total solar
eclipse will happen near you

00:03:03.740 --> 00:03:04.920
look it up online.

00:03:04.920 --> 00:03:06.260
Scientists are able to calculate

00:03:06.260 --> 00:03:08.810
when solar eclipses will
happen centuries in advance.

00:03:08.810 --> 00:03:11.150
So you can start planning far ahead.

00:03:11.150 --> 00:03:12.480
Personally, I'll need to travel

00:03:12.480 --> 00:03:14.900
if I want to see a total
solar eclipse anytime soon

00:03:14.900 --> 00:03:16.080
because the next one visible

00:03:16.080 --> 00:03:19.613
in my hometown is on September 14th, 2099.


Global winds and currents

WEBVTT
Kind: captions
Language: en

00:00:00.360 --> 00:00:01.950
- [Instructor] One of
my favorite things to do

00:00:01.950 --> 00:00:02.980
is go camping.

00:00:02.980 --> 00:00:05.840
For me, there's nothing
better than getting outside,

00:00:05.840 --> 00:00:07.400
breathing in some fresh air

00:00:07.400 --> 00:00:09.940
and taking a swim in my favorite river.

00:00:09.940 --> 00:00:11.520
Have you ever jumped into a river

00:00:11.520 --> 00:00:13.870
and felt that the deeper, cooler water

00:00:13.870 --> 00:00:16.040
closer to your feet was moving faster

00:00:16.040 --> 00:00:18.880
than the shallow, warmer
water at your knees?

00:00:18.880 --> 00:00:20.130
That's a current,

00:00:20.130 --> 00:00:22.040
which is the a word we use to describe

00:00:22.040 --> 00:00:23.760
how water or even air

00:00:23.760 --> 00:00:26.830
flows within a larger
body of water or air,

00:00:26.830 --> 00:00:28.790
but what causes a current?

00:00:28.790 --> 00:00:30.920
Well, let's start with the Sun.

00:00:30.920 --> 00:00:33.750
The Sun actually heats Earth unevenly.

00:00:33.750 --> 00:00:35.940
We know that it's hotter near the equator

00:00:35.940 --> 00:00:39.050
and it gets colder as
you go towards the poles.

00:00:39.050 --> 00:00:40.040
Near the equator,

00:00:40.040 --> 00:00:43.260
the Sun's rays hit Earth
surface more directly,

00:00:43.260 --> 00:00:44.750
while near the poles,

00:00:44.750 --> 00:00:47.800
the Sun's rays hit Earth
surface less directly.

00:00:47.800 --> 00:00:48.750
In both regions,

00:00:48.750 --> 00:00:51.270
the same amount of solar
energy is heading Earth,

00:00:51.270 --> 00:00:54.540
but near the equator, this
energy is concentrated

00:00:54.540 --> 00:00:56.010
into a smaller area

00:00:56.010 --> 00:00:59.380
and near the poles it's
spread out over a larger area.

00:00:59.380 --> 00:01:02.840
So the regions near the
equator get more solar energy,

00:01:02.840 --> 00:01:04.360
which makes them warmer

00:01:04.360 --> 00:01:07.420
and the regions near the
poles get less solar energy,

00:01:07.420 --> 00:01:08.713
which makes them cooler.

00:01:10.040 --> 00:01:13.490
This uneven heating at Earth
also affects air pressure,

00:01:13.490 --> 00:01:15.710
where it's cooler near the poles,

00:01:15.710 --> 00:01:19.440
cool air will sink making
the air pressure high,

00:01:19.440 --> 00:01:21.770
but where it's warmer near the equator,

00:01:21.770 --> 00:01:25.180
warm air will rise
resulting in low pressure.

00:01:25.180 --> 00:01:27.300
This is where the terms low-pressure cells

00:01:27.300 --> 00:01:29.430
and high-pressure cells come from.

00:01:29.430 --> 00:01:31.930
The low-pressure warmer air at the equator

00:01:31.930 --> 00:01:34.580
rises into the upper
atmosphere where it cools

00:01:34.580 --> 00:01:36.950
and flows away towards higher latitudes

00:01:36.950 --> 00:01:38.710
away from the equator.

00:01:38.710 --> 00:01:40.640
Because the air is now cooler,

00:01:40.640 --> 00:01:41.900
it starts to sink again

00:01:41.900 --> 00:01:45.460
and creates a high-pressure
band near these latitudes.

00:01:45.460 --> 00:01:47.460
This process repeats and creates a pattern

00:01:47.460 --> 00:01:48.950
of high and low-pressure bands

00:01:48.950 --> 00:01:50.683
from the equator to the poles.

00:01:51.940 --> 00:01:54.360
We know that air flows
from areas of high pressure

00:01:54.360 --> 00:01:56.200
to areas of low pressure.

00:01:56.200 --> 00:01:59.050
This creates air occurrence or winds.

00:01:59.050 --> 00:02:00.520
Now you might think that these winds

00:02:00.520 --> 00:02:01.840
would blow in straight lines

00:02:01.840 --> 00:02:03.890
from high to low-pressure areas.

00:02:03.890 --> 00:02:05.890
But the global wind patterns,

00:02:05.890 --> 00:02:07.700
which we call prevailing winds,

00:02:07.700 --> 00:02:10.640
look like they curved the right
in the Northern Hemisphere

00:02:10.640 --> 00:02:12.990
and to the left in the
Southern Hemisphere.

00:02:12.990 --> 00:02:15.860
This curving has to do
with the rotation of Earth

00:02:15.860 --> 00:02:17.823
and is called the Coriolis effect.

00:02:19.750 --> 00:02:21.210
As these prevailing winds

00:02:21.210 --> 00:02:23.870
blow across the surface
of the land and water,

00:02:23.870 --> 00:02:26.120
they also pushed against
the surface of the ocean

00:02:26.120 --> 00:02:28.630
and produce wind-driven surface currents,

00:02:28.630 --> 00:02:30.960
which helped to move ocean water.

00:02:30.960 --> 00:02:32.270
Here's what the global pattern

00:02:32.270 --> 00:02:34.363
of ocean surface currents looks like.

00:02:35.350 --> 00:02:36.610
Like wind currents,

00:02:36.610 --> 00:02:38.770
ocean surface currents are also curved

00:02:38.770 --> 00:02:40.720
due to the Coriolis effect.

00:02:40.720 --> 00:02:42.060
We can see that in these currents

00:02:42.060 --> 00:02:44.150
that are traveling north and south,

00:02:44.150 --> 00:02:46.480
which curved to the right
in the Northern Hemisphere

00:02:46.480 --> 00:02:49.160
and to the left in the
Southern Hemisphere.

00:02:49.160 --> 00:02:51.810
Together as these surface
currents of the ocean connect,

00:02:51.810 --> 00:02:53.940
they formed giant rotating systems

00:02:53.940 --> 00:02:56.150
of ocean currents called gyres.

00:02:56.150 --> 00:02:57.640
The currents that drive these gyres

00:02:57.640 --> 00:02:59.850
extend from the surface
to about one kilometer

00:02:59.850 --> 00:03:01.060
down into the ocean

00:03:01.060 --> 00:03:04.030
and helped move water
all around the globe.

00:03:04.030 --> 00:03:06.340
But these gyres aren't just moving water,

00:03:06.340 --> 00:03:08.440
they're moving heat energy as well.

00:03:08.440 --> 00:03:10.720
Water is pretty good at holding onto heat

00:03:10.720 --> 00:03:12.400
it absorbs from the Sun.

00:03:12.400 --> 00:03:15.410
So as the water in our
oceans moves around the world

00:03:15.410 --> 00:03:17.230
through this gyre circulation,

00:03:17.230 --> 00:03:19.600
the water also carries heat.

00:03:19.600 --> 00:03:21.760
Here, warm water generally moves

00:03:21.760 --> 00:03:23.680
from the equator to the poles

00:03:23.680 --> 00:03:26.563
and cold water moves from
the poles to the equator.

00:03:27.980 --> 00:03:30.470
But the ocean has other deeper currents

00:03:30.470 --> 00:03:33.900
that are affected by differences
in temperature and density.

00:03:33.900 --> 00:03:36.390
Remember how we talked
about areas heated directly

00:03:36.390 --> 00:03:38.260
and less directly by the Sun?

00:03:38.260 --> 00:03:41.430
And how that results in low
and high-pressure areas?

00:03:41.430 --> 00:03:43.960
Same thing with water,
except that water density

00:03:43.960 --> 00:03:46.870
is affected by both
temperature and salinity,

00:03:46.870 --> 00:03:49.410
which is a measure of
how salty the ocean is.

00:03:49.410 --> 00:03:51.810
Cooler and saltier water is more dense,

00:03:51.810 --> 00:03:54.420
so it tends to sink, just like cool air.

00:03:54.420 --> 00:03:57.310
Whereas warmer and less
salty water is less dense

00:03:57.310 --> 00:03:59.740
and tends to rise, just like warm air.

00:03:59.740 --> 00:04:02.050
So with these deeper ocean currents,

00:04:02.050 --> 00:04:05.180
water actually moves
vertically or up and down.

00:04:05.180 --> 00:04:08.820
For example, water near
the poles gets very cold.

00:04:08.820 --> 00:04:12.230
It also gets very salty,
because when sea ice is formed,

00:04:12.230 --> 00:04:14.440
the salt can't go into the ice.

00:04:14.440 --> 00:04:17.360
Instead, the salt stays
behind in the water

00:04:17.360 --> 00:04:20.890
and so the water gets
saltier or more saline.

00:04:20.890 --> 00:04:23.290
Together, the coldness and salinity

00:04:23.290 --> 00:04:24.980
makes the water very dense

00:04:24.980 --> 00:04:28.010
causing it to sink deep into the ocean.

00:04:28.010 --> 00:04:29.710
And other parts of the ocean,

00:04:29.710 --> 00:04:32.060
wind drags deep water up to the surface

00:04:32.060 --> 00:04:34.120
and a process called upwelling.

00:04:34.120 --> 00:04:35.860
These vertical currents are connected

00:04:35.860 --> 00:04:39.723
by horizontal currents at the
surface and in the deep ocean.

00:04:40.780 --> 00:04:41.730
Collectively,

00:04:41.730 --> 00:04:43.440
this system of currents is known

00:04:43.440 --> 00:04:45.650
as the overturning circulation.

00:04:45.650 --> 00:04:46.840
You might also hear it called

00:04:46.840 --> 00:04:49.030
the global ocean conveyor belts.

00:04:49.030 --> 00:04:52.070
So here's a map showing the
overturning circulation.

00:04:52.070 --> 00:04:54.080
This map might look a little bit strange,

00:04:54.080 --> 00:04:56.960
but here we're looking at
Earth from the South Pole.

00:04:56.960 --> 00:04:59.440
So Australia and the
southern tips of Africa

00:04:59.440 --> 00:05:02.540
and South America are closes
to the center of the map,

00:05:02.540 --> 00:05:05.260
while Europe, most of
Asia and North America

00:05:05.260 --> 00:05:07.320
are at the edges.

00:05:07.320 --> 00:05:09.290
Now, if you follow the currents

00:05:09.290 --> 00:05:11.380
in the overturning circulation,

00:05:11.380 --> 00:05:14.690
you can see that they flow
all over the world's oceans.

00:05:14.690 --> 00:05:17.060
From the southern ocean
around the South Pole,

00:05:17.060 --> 00:05:19.050
to the Pacific, the Indian

00:05:19.050 --> 00:05:21.590
and all the way into the North Atlantic.

00:05:21.590 --> 00:05:24.000
Like the currents in the gyre circulation,

00:05:24.000 --> 00:05:26.060
the currents in the
overturning circulation

00:05:26.060 --> 00:05:30.303
also carry and disperse heat
energy all around the world.

00:05:30.303 --> 00:05:33.880
Here I am, back in my
favorite river, waiting around

00:05:33.880 --> 00:05:37.420
and enjoying currents of cool
water flowing around my feet.

00:05:37.420 --> 00:05:39.641
And even though this river is small,

00:05:39.641 --> 00:05:41.460
the currents that flow through it

00:05:41.460 --> 00:05:43.730
are similar to the global
wind and ocean currents

00:05:43.730 --> 00:05:45.810
that flow all around the world.

00:05:45.810 --> 00:05:49.360
So these currents connect in
our atmosphere and oceans,

00:05:49.360 --> 00:05:51.850
which means that we are all connected.

00:05:51.850 --> 00:05:54.273
So currents connect us all.


Weather

WEBVTT
Kind: captions
Language: en

00:00:00.130 --> 00:00:01.810
- [Narrator] Have you ever
gotten up in a good mood,

00:00:01.810 --> 00:00:03.880
put on your absolute favorite outfit,

00:00:03.880 --> 00:00:06.110
went outside to have a fun day in the sun,

00:00:06.110 --> 00:00:07.690
and then ended up soaking wet,

00:00:07.690 --> 00:00:09.760
caught in a sudden rainstorm?

00:00:09.760 --> 00:00:11.150
Yeah, same.

00:00:11.150 --> 00:00:13.500
Unfortunately, we can't
control the weather.

00:00:13.500 --> 00:00:14.880
Weather changes from day to day

00:00:14.880 --> 00:00:15.910
and from place to place,

00:00:15.910 --> 00:00:18.300
so scientists have to consider
a lot of different factors

00:00:18.300 --> 00:00:19.800
to understand it.

00:00:19.800 --> 00:00:21.520
Weather can refer to humidity,

00:00:21.520 --> 00:00:23.520
or amount of water vapor in the air,

00:00:23.520 --> 00:00:24.430
temperature,

00:00:24.430 --> 00:00:25.400
air pressure,

00:00:25.400 --> 00:00:26.233
wind,

00:00:26.233 --> 00:00:29.390
and, of course, precipitation
like rain or snow.

00:00:29.390 --> 00:00:31.860
When heat from the sun enters
Earth's lower atmosphere,

00:00:31.860 --> 00:00:34.540
it affects the temperature
and humidity of the air.

00:00:34.540 --> 00:00:35.810
As this National Aeronautics

00:00:35.810 --> 00:00:38.040
and Space Administration map shows,

00:00:38.040 --> 00:00:39.740
air masses with certain characteristics

00:00:39.740 --> 00:00:41.640
tend to form in similar places.

00:00:41.640 --> 00:00:43.600
There's many ways to
classify these air masses,

00:00:43.600 --> 00:00:44.760
but to keep it simple,

00:00:44.760 --> 00:00:46.710
these blue blobs represent
colder air masses,

00:00:46.710 --> 00:00:48.410
which tend to be closer to the poles,

00:00:48.410 --> 00:00:50.800
and the red blobs
represent warm air masses,

00:00:50.800 --> 00:00:52.380
which are often found near the equator,

00:00:52.380 --> 00:00:54.830
where the sun's energy is strongest.

00:00:54.830 --> 00:00:55.920
The qualities of an air mass

00:00:55.920 --> 00:00:57.950
may also depend on where it forms.

00:00:57.950 --> 00:01:00.680
Air masses that form over land
tend to have less humidity

00:01:00.680 --> 00:01:03.170
than those that form over an ocean.

00:01:03.170 --> 00:01:06.430
Air masses can even change
characteristics as they move.

00:01:06.430 --> 00:01:08.780
For example, when a very
cold and dry air mass

00:01:08.780 --> 00:01:09.810
moves over the ocean,

00:01:09.810 --> 00:01:11.620
it will likely pick up
warmth and moisture,

00:01:11.620 --> 00:01:13.630
transforming it into a slightly warmer

00:01:13.630 --> 00:01:14.943
and more humid air mass.

00:01:15.860 --> 00:01:17.380
Weather results from these air masses

00:01:17.380 --> 00:01:19.380
moving from areas with high air pressure

00:01:19.380 --> 00:01:21.600
to areas with low air pressure.

00:01:21.600 --> 00:01:22.460
When this happens,

00:01:22.460 --> 00:01:25.350
a high- or low-pressure system can form.

00:01:25.350 --> 00:01:28.060
A high-pressure system has
higher pressure at its center

00:01:28.060 --> 00:01:29.460
than the areas around it,

00:01:29.460 --> 00:01:31.630
so air moves out from the center.

00:01:31.630 --> 00:01:34.800
High-pressure systems
typically bring clear skies.

00:01:34.800 --> 00:01:37.290
A low-pressure system has
lower pressure at its center

00:01:37.290 --> 00:01:38.610
than the areas around it,

00:01:38.610 --> 00:01:41.640
so air is sucked into
the center of the system.

00:01:41.640 --> 00:01:45.150
Low-pressure systems typically
bring more intense weather.

00:01:45.150 --> 00:01:46.600
Why is this?

00:01:46.600 --> 00:01:48.140
Well, low-pressure systems

00:01:48.140 --> 00:01:51.020
are often associated
with what we call fronts.

00:01:51.020 --> 00:01:52.610
A front is a boundary that forms

00:01:52.610 --> 00:01:54.530
when air masses of different
temperatures collide

00:01:54.530 --> 00:01:56.080
near Earth's surface.

00:01:56.080 --> 00:01:57.500
Different types of fronts can then form

00:01:57.500 --> 00:01:59.960
depending on how those air masses meet.

00:01:59.960 --> 00:02:01.070
A warm front occurs

00:02:01.070 --> 00:02:04.240
when a warm air mass moves in
to a replace a cold air mass.

00:02:04.240 --> 00:02:06.340
Since warm air is less
dense than cold air,

00:02:06.340 --> 00:02:08.060
it rises above the colder air,

00:02:08.060 --> 00:02:11.170
causing a lot of overcast
skies, moderate rain or snow,

00:02:11.170 --> 00:02:13.110
and warm temperatures.

00:02:13.110 --> 00:02:15.590
A cold front occurs when
a cold air mass moves in

00:02:15.590 --> 00:02:17.460
to replace a warm air mass.

00:02:17.460 --> 00:02:20.800
The dense cold air pushes
the warmer air mass upward,

00:02:20.800 --> 00:02:22.690
causing larger clouds to build overhead

00:02:22.690 --> 00:02:24.610
and bringing heavy rain or thunderstorms,

00:02:24.610 --> 00:02:27.640
strong winds, and cool
temperatures with them.

00:02:27.640 --> 00:02:29.050
Weather is so complex

00:02:29.050 --> 00:02:31.750
that it can be difficult to
predict what will happen next.

00:02:31.750 --> 00:02:33.870
Luckily, scientists have
developed technologies

00:02:33.870 --> 00:02:35.380
that help model weather patterns

00:02:35.380 --> 00:02:37.080
so we can all make more informed choices

00:02:37.080 --> 00:02:39.470
about what to expect when we go outside.

00:02:39.470 --> 00:02:40.790
To do that, they set up tools

00:02:40.790 --> 00:02:42.410
like satellites and Doppler radar

00:02:42.410 --> 00:02:44.320
to observe atmospheric conditions

00:02:44.320 --> 00:02:47.000
such as wind speed,
temperature, air pressure,

00:02:47.000 --> 00:02:49.350
and nearby geographic features.

00:02:49.350 --> 00:02:51.710
They can input the data they
record into computer models,

00:02:51.710 --> 00:02:54.970
which can use that information
to predict future weather.

00:02:54.970 --> 00:02:56.530
Have you ever seen a map like this

00:02:56.530 --> 00:02:58.350
used in a weather forecast?

00:02:58.350 --> 00:03:01.210
This National Oceanic and
Atmospheric Administration map

00:03:01.210 --> 00:03:03.420
uses data from a Doppler radar station

00:03:03.420 --> 00:03:05.360
that measured the
progression of a severe storm

00:03:05.360 --> 00:03:07.630
over the Northeastern United States.

00:03:07.630 --> 00:03:09.470
The most intense central
parts of the storm

00:03:09.470 --> 00:03:10.510
are shown in red,

00:03:10.510 --> 00:03:11.670
with colors down the rainbow

00:03:11.670 --> 00:03:15.250
representing progressively less
intense parts of the storm.

00:03:15.250 --> 00:03:16.500
As technology has advanced,

00:03:16.500 --> 00:03:18.550
these weather reports
have gotten more accurate,

00:03:18.550 --> 00:03:20.350
but with so many factors to consider

00:03:20.350 --> 00:03:22.800
weather is still only
somewhat predictable.

00:03:22.800 --> 00:03:23.870
That's why you'll always hear

00:03:23.870 --> 00:03:25.600
probabilistic weather predictions,

00:03:25.600 --> 00:03:26.610
providing a percentage

00:03:26.610 --> 00:03:28.580
that refers to how confident the model is

00:03:28.580 --> 00:03:30.270
that the prediction will happen.

00:03:30.270 --> 00:03:31.680
If your local weather forecast

00:03:31.680 --> 00:03:34.100
says there's a 30% chance of rain,

00:03:34.100 --> 00:03:36.050
it's less likely, but still possible

00:03:36.050 --> 00:03:37.540
that you're going to get rain.

00:03:37.540 --> 00:03:40.430
If it says there's a 90%
chance of snow on another day,

00:03:40.430 --> 00:03:42.740
you're most likely going to get snow.

00:03:42.740 --> 00:03:44.610
Even if weather
predictions aren't perfect,

00:03:44.610 --> 00:03:46.990
it's amazing that scientists
figured out how to understand

00:03:46.990 --> 00:03:49.200
such a complicated phenomenon.

00:03:49.200 --> 00:03:50.650
Without modern tools and models,

00:03:50.650 --> 00:03:52.790
it would be much more
difficult for us to plan ahead

00:03:52.790 --> 00:03:55.140
and be prepared for
possible weather hazards.

00:03:55.140 --> 00:03:56.870
Next time you have a
fancy day out planned,

00:03:56.870 --> 00:03:59.310
be sure to check the weather
forecast before you go.

00:03:59.310 --> 00:04:01.100
If it says there's a
decent chance of rain,

00:04:01.100 --> 00:04:02.450
don't forget your umbrella.


Refraction and frequency

WEBVTT
Kind: captions
Language: en

00:00:00.400 --> 00:00:02.730
- [Instructor] When light is
going through a uniform medium,

00:00:02.730 --> 00:00:03.740
like the air,

00:00:03.740 --> 00:00:05.580
or as we know, light
can go through a vacuum,

00:00:05.580 --> 00:00:06.740
so nothing at all,

00:00:06.740 --> 00:00:09.280
we imagine it going in a straight line,

00:00:09.280 --> 00:00:12.350
but we see something really
interesting happening here.

00:00:12.350 --> 00:00:14.760
When it hits this glass prism,

00:00:14.760 --> 00:00:16.540
I know it just looks like
a gray triangle to you,

00:00:16.540 --> 00:00:19.940
but imagine it as a
triangular piece of glass,

00:00:19.940 --> 00:00:22.300
and it's hitting it at an angle.

00:00:22.300 --> 00:00:24.300
What this animation shows us

00:00:24.300 --> 00:00:27.670
is that the path of the
light actually gets bent,

00:00:27.670 --> 00:00:29.740
and not only does it get bent,

00:00:29.740 --> 00:00:32.060
but the different frequencies of the light

00:00:32.060 --> 00:00:34.590
get bent by different amounts.

00:00:34.590 --> 00:00:36.300
Now, if you were to look
at this with your eyes,

00:00:36.300 --> 00:00:38.610
you wouldn't be able to
see the actual waves,

00:00:38.610 --> 00:00:41.260
like we're seeing in this
diagram right over here.

00:00:41.260 --> 00:00:44.430
You would just see how
your brain or how your mind

00:00:44.430 --> 00:00:46.420
perceives the various frequencies,

00:00:46.420 --> 00:00:48.790
and that's why they made
the higher frequencies here

00:00:48.790 --> 00:00:50.970
more like a violet or a purple color,

00:00:50.970 --> 00:00:53.080
and that's why they made
the lower frequencies here

00:00:53.080 --> 00:00:54.640
more of a red color,

00:00:54.640 --> 00:00:56.930
because that's how your brain or your mind

00:00:56.930 --> 00:00:58.120
would perceive them.

00:00:58.120 --> 00:01:00.810
But you can see as this light goes from,

00:01:00.810 --> 00:01:03.290
let's say the vacuum to this prism,

00:01:03.290 --> 00:01:05.200
to this crystal or this glass,

00:01:05.200 --> 00:01:08.520
the high-frequency light gets bent more,

00:01:08.520 --> 00:01:11.540
and the low-frequency light,
which still gets bent,

00:01:11.540 --> 00:01:13.160
gets bent less,

00:01:13.160 --> 00:01:15.320
and then that essentially spreads out

00:01:15.320 --> 00:01:16.690
all of the wavelengths.

00:01:16.690 --> 00:01:18.010
When we have white light,

00:01:18.010 --> 00:01:20.760
it has all of the visible
wavelengths in it,

00:01:20.760 --> 00:01:23.100
but when it hits a prism like this,

00:01:23.100 --> 00:01:25.480
if you imagine a triangular
piece of glass or crystal

00:01:25.480 --> 00:01:26.870
and it hits it at an angle,

00:01:26.870 --> 00:01:28.900
well, then the different
wavelengths spread out,

00:01:28.900 --> 00:01:31.410
and if you were to put
a piece of paper here,

00:01:31.410 --> 00:01:33.350
you would see a rainbow,

00:01:33.350 --> 00:01:36.290
and that's actually how
rainbows are formed.

00:01:36.290 --> 00:01:40.900
A bunch of water particles
in the air refract light

00:01:40.900 --> 00:01:42.640
exactly like this.

00:01:42.640 --> 00:01:44.650
This process of when light goes

00:01:44.650 --> 00:01:47.960
from one transparent medium
to another, or a vacuum,

00:01:47.960 --> 00:01:49.310
to some other medium

00:01:49.310 --> 00:01:52.180
that it can travel through
that's transparent,

00:01:52.180 --> 00:01:54.760
if it hits it in an
angle, it can get bent,

00:01:54.760 --> 00:01:56.810
which is what we called refraction.

00:01:56.810 --> 00:01:58.740
This is why when you
look at a cup of water

00:01:58.740 --> 00:02:00.610
or at a pool at an angle,

00:02:00.610 --> 00:02:02.910
you're not seeing
directly through the pool.

00:02:02.910 --> 00:02:04.523
The image gets distorted.


Creativity break: How can we combine ways of thinking in problem solving?

WEBVTT
Kind: captions
Language: en

00:00:00.639 --> 00:00:03.222
(upbeat music)

00:00:11.420 --> 00:00:14.360
- One of the newest ways of
thinking about problem solving

00:00:14.360 --> 00:00:19.100
for me is something that my
math professor would tell me.

00:00:19.100 --> 00:00:22.570
He would say don't be afraid to be stuck.

00:00:22.570 --> 00:00:25.130
And I think that a lot of the time

00:00:25.130 --> 00:00:27.640
when we are doing math and we get stuck,

00:00:27.640 --> 00:00:32.010
it's like sometimes
you can feel like, wow,

00:00:32.010 --> 00:00:34.870
this is a reflection of me
and my mathematical abilities.

00:00:34.870 --> 00:00:36.760
Maybe I shouldn't be doing math.

00:00:36.760 --> 00:00:38.060
But really a lot of the time

00:00:38.060 --> 00:00:40.840
it's just an indication
that you need to spend more

00:00:40.840 --> 00:00:43.870
time doing the math or figuring out

00:00:43.870 --> 00:00:45.270
what the problem is exactly.

00:00:45.270 --> 00:00:48.000
If you haven't gotten
stuck yet, then I mean,

00:00:48.000 --> 00:00:50.430
you probably will get stuck at some point.

00:00:50.430 --> 00:00:53.330
So being stuck is just a part of math

00:00:53.330 --> 00:00:57.280
and it's kind of learning what to do when

00:00:57.280 --> 00:01:01.700
you are stuck is a really
big part of being creative

00:01:01.700 --> 00:01:05.100
in math and being able to
solve problems in the future.

00:01:05.100 --> 00:01:10.100
- One example that I often
use is I often try to

00:01:10.700 --> 00:01:15.700
solve problems both in the
traditional algebraic way

00:01:16.780 --> 00:01:20.570
but I also try to visualize problems

00:01:20.570 --> 00:01:24.330
in 2D and 3D space to
solve them more visually.

00:01:24.330 --> 00:01:27.020
And so I think the more ways

00:01:27.020 --> 00:01:29.970
that you can figure out
how to solve a problem,

00:01:29.970 --> 00:01:32.470
the more ways that you can eventually

00:01:32.470 --> 00:01:35.220
save in your toolbox and use later on

00:01:35.220 --> 00:01:37.380
to solve other problems.

00:01:37.380 --> 00:01:40.120
- There's lots of different
tools and resources

00:01:40.120 --> 00:01:43.520
like apps and puzzle games
that are gonna help you

00:01:43.520 --> 00:01:45.470
think about problems in new ways

00:01:45.470 --> 00:01:48.380
and help develop that
critical thinking that you

00:01:48.380 --> 00:01:50.560
need to be able to apply your skills

00:01:50.560 --> 00:01:52.900
to a lot of different areas.

00:01:52.900 --> 00:01:54.500
And sometimes even starting

00:01:54.500 --> 00:01:56.460
at the answer and working backwards

00:01:56.460 --> 00:01:59.250
through the problem can
help you see a different way

00:01:59.250 --> 00:02:01.110
of getting to the answer.

00:02:01.110 --> 00:02:02.370
- Students can combine new ways

00:02:02.370 --> 00:02:03.820
of thinking about problem solving

00:02:03.820 --> 00:02:05.560
by trying to look at it
from different angles.

00:02:05.560 --> 00:02:07.320
Anytime you approach a problem

00:02:07.320 --> 00:02:09.850
if you're just looking at
it from your perspective,

00:02:09.850 --> 00:02:13.070
you're not gonna get a holistic
view of the solution space.

00:02:13.070 --> 00:02:16.510
So try to have perspectives
and look at the problem

00:02:16.510 --> 00:02:18.880
from multiple angles to understand

00:02:18.880 --> 00:02:20.730
all the ways in which it could be viewed.

00:02:20.730 --> 00:02:22.920
The more holistically you view a problem,

00:02:22.920 --> 00:02:24.470
the more paths you look at,

00:02:24.470 --> 00:02:25.840
the more efficient and effective

00:02:25.840 --> 00:02:27.340
you're gonna be at solving it.


Creativity break: What can we do to expand our creative skills?

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(light upbeat music)

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(keyboard keys clicking)

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- There are so many ways

00:00:12.540 --> 00:00:15.200
that you can expand your
creative and math skills

00:00:15.200 --> 00:00:17.060
without even really realizing
that you're doing it.

00:00:17.060 --> 00:00:20.810
Like for me, I'm a big board game fan

00:00:20.810 --> 00:00:25.270
and I realize that there's so
many games that involve math

00:00:25.270 --> 00:00:28.350
and learning how to solve problems.

00:00:28.350 --> 00:00:32.480
And sometimes like, just
when you're cooking.

00:00:32.480 --> 00:00:33.520
I love to bake.

00:00:33.520 --> 00:00:36.690
And so I feel like I'm
constantly using like fractions

00:00:36.690 --> 00:00:38.630
and learning how to do proportions,

00:00:38.630 --> 00:00:40.980
just because I'm doing things that I love.

00:00:40.980 --> 00:00:43.380
So I feel like the best way to expand

00:00:43.380 --> 00:00:45.720
your mathematical and creative skills

00:00:45.720 --> 00:00:47.570
are just doing what you love to do

00:00:47.570 --> 00:00:50.460
because probably it has
some kind of math in it

00:00:50.460 --> 00:00:52.980
and some kind of creativity.

00:00:52.980 --> 00:00:56.300
- Try to connect what you're
learning to your real life.

00:00:56.300 --> 00:00:58.900
It's really easy to be in the classroom

00:00:58.900 --> 00:01:00.780
and think that it's siloed

00:01:00.780 --> 00:01:03.096
and it's orthogonal from
the world around you.

00:01:03.096 --> 00:01:07.050
The more we can connect what
we're learning in the classroom

00:01:07.050 --> 00:01:10.720
to our real life, either
via sports or entertainment,

00:01:10.720 --> 00:01:13.210
politics, news, whatever.

00:01:13.210 --> 00:01:15.730
The connection that you make
between math and your real life

00:01:15.730 --> 00:01:17.910
will really help you appreciate the skills

00:01:17.910 --> 00:01:20.850
and the methods and find
ways to transfer them

00:01:20.850 --> 00:01:23.367
outside of just the classroom alone.

00:01:23.367 --> 00:01:26.450
(light upbeat music)


Creativity break: How are math and creativity changing the world?

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(light music)

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(typewriter typing)

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- Maths underpins
everything in our universe,

00:00:13.970 --> 00:00:17.570
so it impacts every corner of our society.

00:00:17.570 --> 00:00:19.760
But over the past decade in particular,

00:00:19.760 --> 00:00:22.200
the advances in computer technology

00:00:22.200 --> 00:00:24.390
and the introduction of machine learning

00:00:24.390 --> 00:00:27.690
and artificial intelligence
has been massive.

00:00:27.690 --> 00:00:29.470
And we're only learning more and more

00:00:29.470 --> 00:00:32.030
and building better and better systems.

00:00:32.030 --> 00:00:33.920
And maths underpins all of that

00:00:33.920 --> 00:00:36.660
and it's fundamental to
all of those systems.

00:00:36.660 --> 00:00:40.610
And in fact, computer science
is inherently linear algebra,

00:00:40.610 --> 00:00:44.490
so it's really foundational
to those scientific advances.

00:00:44.490 --> 00:00:46.100
- One relatively recent example

00:00:46.100 --> 00:00:49.350
that really inspired me
was the first real photo

00:00:49.350 --> 00:00:53.170
that scientists were able
to capture of a black hole,

00:00:53.170 --> 00:00:57.250
those mysterious remnants
of giant stars that lurk

00:00:57.250 --> 00:00:58.920
all over the universe.

00:00:58.920 --> 00:01:01.670
And it is the way the scientists
used creativity and math

00:01:01.670 --> 00:01:04.450
to solve the problem
that was so fascinating.

00:01:04.450 --> 00:01:06.550
You see, these black holes are do distant

00:01:06.550 --> 00:01:09.590
that there is no single
telescope that is large enough

00:01:09.590 --> 00:01:11.430
to be able to actually see them.

00:01:11.430 --> 00:01:14.300
And the scientists came
up with this clever idea,

00:01:14.300 --> 00:01:17.580
creating a network of small
telescopes distributed

00:01:17.580 --> 00:01:19.750
all across the globe
that were synchronized

00:01:19.750 --> 00:01:24.040
to capture and focus the
same object at the same time,

00:01:24.040 --> 00:01:26.880
creating a giant virtual telescope.

00:01:26.880 --> 00:01:29.570
Now, the aperture of this
giant virtual telescope

00:01:29.570 --> 00:01:33.890
is nearly the same size as
the diameter of the Earth.

00:01:33.890 --> 00:01:35.050
And with that in place,

00:01:35.050 --> 00:01:37.150
the scientists and engineers
were able to capture

00:01:37.150 --> 00:01:39.000
all the bits and pieces of data

00:01:39.000 --> 00:01:41.440
and put it all together
into the first image

00:01:41.440 --> 00:01:44.560
of a black hole that is
53 million light-years,

00:01:44.560 --> 00:01:48.830
which is 318 quintillion miles away.

00:01:48.830 --> 00:01:51.729
Now, that's an impressive
use of creativity and maths.

00:01:51.729 --> 00:01:55.027
(light music continues)


Creativity break: Why is algebra important to learn?

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(marker scratching)

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(gentle upbeat music)

00:00:09.870 --> 00:00:13.490
- Algebra is really the unifying thread

00:00:13.490 --> 00:00:16.100
of almost all of mathematics.

00:00:16.100 --> 00:00:18.250
You may think algebra is boring,

00:00:18.250 --> 00:00:22.490
but it is the one tool you can
use to not only understand,

00:00:22.490 --> 00:00:24.580
but unlock the universe.

00:00:24.580 --> 00:00:27.830
Creative algebra is used
in computer game design.

00:00:27.830 --> 00:00:31.810
It powers how artificial
intelligence works.

00:00:31.810 --> 00:00:34.880
Mastering algebra will
provide you with the ability

00:00:34.880 --> 00:00:38.287
to decode and understand
many complex systems.

00:00:38.287 --> 00:00:41.130
In my opinion, if you can master algebra,

00:00:41.130 --> 00:00:42.330
you can master anything.


Creativity break: What do you do to get into your creative zone?

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(soft music)

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(marker scratches)

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(keyboard taps)

00:00:10.300 --> 00:00:14.050
- Whenever I wanna come up
with a solution to a problem

00:00:14.050 --> 00:00:15.330
and I don't have it,

00:00:15.330 --> 00:00:20.100
my immediate reaction is to
go outside and go on a walk.

00:00:20.100 --> 00:00:22.173
I love walking in all kinds of weather.

00:00:25.348 --> 00:00:27.203
I feel like with the peace and calm,

00:00:27.203 --> 00:00:31.100
moving away from the problem
and stepping away from it,

00:00:31.100 --> 00:00:35.200
sometimes I get way better
ideas and it inspires me.

00:00:35.200 --> 00:00:36.570
But, I also think there's
something to be said

00:00:36.570 --> 00:00:38.930
about not being inspired.

00:00:38.930 --> 00:00:41.110
Like, not always as amazing.

00:00:41.110 --> 00:00:44.770
I feel like sometimes I
get struck with inspiration

00:00:44.770 --> 00:00:47.900
for how I want to explain
a Khan Academy video

00:00:47.900 --> 00:00:49.720
or how I wanna approach a piece of art

00:00:49.720 --> 00:00:52.830
or how I want to approach a math problem,

00:00:52.830 --> 00:00:54.540
but sometimes it doesn't come.

00:00:54.540 --> 00:00:56.830
And so I feel like what
the best solution is

00:00:56.830 --> 00:00:58.770
when you are trying to get
into that creative zone

00:00:58.770 --> 00:01:00.660
and you can't, is just do it

00:01:00.660 --> 00:01:03.470
and try to do something anyway.

00:01:03.470 --> 00:01:06.960
Like write something or
write your equations,

00:01:06.960 --> 00:01:08.380
try to figure it out.

00:01:08.380 --> 00:01:10.530
And if you make mistakes, that's okay,

00:01:10.530 --> 00:01:11.830
because it's something to jump off of

00:01:11.830 --> 00:01:16.020
and sometimes seeing what you
already know down on paper

00:01:16.020 --> 00:01:18.040
can help you come up with better ideas

00:01:18.040 --> 00:01:19.700
and can help you be more creative.

00:01:19.700 --> 00:01:22.010
- Forcing yourself to
just conjure a solution,

00:01:22.010 --> 00:01:23.360
simply does not work.

00:01:23.360 --> 00:01:25.130
Instead, take a break from the task.

00:01:25.130 --> 00:01:26.070
Pick something else up,

00:01:26.070 --> 00:01:29.000
like a physical sport or even video games.

00:01:29.000 --> 00:01:31.060
And then come back to
the original problem.

00:01:31.060 --> 00:01:32.838
That can do wonders.

00:01:32.838 --> 00:01:35.255
(soft music)


Creativity break: How does creativity play a role in your everyday life?

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(upbeat music)

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- Creativity is really important for me

00:00:11.830 --> 00:00:14.610
as like a future job, as
a part of my future job

00:00:14.610 --> 00:00:18.370
I would want to do something that changes

00:00:18.370 --> 00:00:21.430
and then I can use problem
solving skills constantly.

00:00:21.430 --> 00:00:24.560
I feel like when I make
animations or when I figure

00:00:24.560 --> 00:00:26.010
out how to explain something,

00:00:28.080 --> 00:00:31.160
I love that because there's
so many different solutions,

00:00:31.160 --> 00:00:33.770
but knowing that you can
try to find and experiment

00:00:33.770 --> 00:00:36.630
with different ones and maybe
create something beautiful

00:00:36.630 --> 00:00:39.990
is really, I don't know, inspiring to me.

00:00:39.990 --> 00:00:42.750
- Mathematicals educational initiative

00:00:42.750 --> 00:00:45.360
that I co-founded with
a fellow mathematician,

00:00:45.360 --> 00:00:46.710
Jess Williams.

00:00:46.710 --> 00:00:50.400
And what we're trying to do is
make maths fun and accessible

00:00:50.400 --> 00:00:54.240
and encourage more girls
to pursue careers in maths.

00:00:54.240 --> 00:00:56.570
So creativity is essential here

00:00:56.570 --> 00:00:57.770
because we're trying to think

00:00:57.770 --> 00:01:01.540
of ways that people will enjoy maths

00:01:01.540 --> 00:01:03.960
and it will be fun and accessible to them.

00:01:03.960 --> 00:01:05.950
So different creative
techniques that we've been

00:01:05.950 --> 00:01:09.750
using are trying to present
mathematical problems

00:01:09.750 --> 00:01:14.500
in fun, short videos, and
that explain the problem

00:01:14.500 --> 00:01:16.850
in a way that everybody will understand

00:01:16.850 --> 00:01:18.900
and will make them want to learn more

00:01:18.900 --> 00:01:21.900
and discover more about the
topics that we're talking about.

00:01:21.900 --> 00:01:23.500
- I'm really lucky

00:01:23.500 --> 00:01:27.470
that I get to be creative
every day in my work

00:01:27.470 --> 00:01:30.840
and I have been since I got
into this field of data science.

00:01:30.840 --> 00:01:33.680
So in general, across the last decade,

00:01:33.680 --> 00:01:36.670
my work has really been about designing

00:01:36.670 --> 00:01:40.840
and testing innovative ways
to capture human behavior

00:01:40.840 --> 00:01:43.230
within game-based assessments.

00:01:43.230 --> 00:01:44.900
So my collaborators and I,

00:01:44.900 --> 00:01:47.930
from the time I was in
graduate school to now,

00:01:47.930 --> 00:01:50.220
use a variety of different
modeling techniques

00:01:50.220 --> 00:01:51.200
from various fields,

00:01:51.200 --> 00:01:55.550
we'll pull things from
engineering, aerospace,

00:01:55.550 --> 00:01:59.480
more basic mathematical models
to help us achieve this goal.

00:01:59.480 --> 00:02:01.100
We get to think outside the box.

00:02:01.100 --> 00:02:04.130
We get to think about how we
can pull in different types

00:02:04.130 --> 00:02:06.980
of thinking from different
fields to help us better

00:02:06.980 --> 00:02:11.980
understand human behavior,
human cognition, learning.

00:02:12.020 --> 00:02:14.600
So it's really exciting and really novel.

00:02:14.600 --> 00:02:17.370
And it's something that because
of the field that I'm in

00:02:17.370 --> 00:02:20.433
I've been able to do this
now for multiple years.


Creativity break: How can people get creative in algebra

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(upbeat music)

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- In order to get more creative,

00:00:12.130 --> 00:00:13.730
I would encourage young people

00:00:13.730 --> 00:00:16.730
to be not afraid of making mistakes.

00:00:16.730 --> 00:00:21.510
It's okay to fail while
exploring a new trail of thought.

00:00:21.510 --> 00:00:23.980
Know that usually there
is more than one solution

00:00:23.980 --> 00:00:25.370
to the problem.

00:00:25.370 --> 00:00:30.370
Math is as much about posing
problems as problem solving.

00:00:30.890 --> 00:00:33.810
And at that point, creativity is noticing

00:00:33.810 --> 00:00:36.060
where there is something
worthwhile investigating.

00:00:36.060 --> 00:00:37.440
- As a student in math,

00:00:37.440 --> 00:00:39.100
I think it's important to remember

00:00:39.100 --> 00:00:44.100
that math isn't just like
random symbols on paper.

00:00:44.100 --> 00:00:46.260
Like math can mean something

00:00:46.260 --> 00:00:49.770
and it's pretty powerful
that you as a student

00:00:49.770 --> 00:00:51.730
can build something that uses math.

00:00:51.730 --> 00:00:53.840
Creativity in math isn't just about

00:00:53.840 --> 00:00:55.430
being able to pluck numbers from the air

00:00:55.430 --> 00:00:57.410
and like, oh yes, I know the solution.

00:00:57.410 --> 00:01:01.310
It's about being able to use problems

00:01:01.310 --> 00:01:02.993
that help with your daily life.