Its altitude is generally at the 250-300 hPa level. A Jet Stream can be several thousand miles long, but only a few hundred miles wide and a few thousand feet in depth. The winds in a Jet Stream are not constant, nor is the direction always west-east.he Sub-tropical jet Stream is located entirely within the tropical air mass and is not associated with any surface fronts. Its location is less variable than the Polar Jet Streams, and its altitude is at around the 200 hPa level.