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Discover what's been hanging
around in our atmosphere.
Well, the atmosphere is
the, you know, layer of air
that completely surrounds
the Earth.
It really changes quite a
bit with altitude as you go
up from the Earth's surface.
There are several
layers of the atmosphere
that each has its
own importance.
The lowest layer,
closest to the ground,
is what we call the troposphere.
This is where all
the weather occurs.
The second layer is
the stratosphere.
It strongly absorbs
ultraviolet radiation
and allows only just a
very small amount to reach
down to the Earth's
surface, where we live.
If it were not for the
stratospheric ozone,
we would suffer terrible
sunburns
and horrendous rates
of skin cancer.
Next, we have the mesosphere,
and there are many important
chemical reactions that go
on there that are, you know,
really driven by sunlight.
And then above that
is the thermosphere,
where most of the molecules
have become charged.
So they're ions, and
that extends out to
at least a hundred
kilometers or more.
Be sure to tell you teacher
to visit the NASA Explorer
Schools Virtual Campus.
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