The second layer of the atmosphere is the stratosphere. The stratosphere reaches from the top of the troposphere to about 50 kilometers above the surface of the Earth.
The stratosphere has a lot less air than the surface of the Earth. It also has only a tiny bit of water vapor. This means there are almost no clouds in the stratosphere. The lack of air also makes it difficult for planes to fly in the stratosphere. However, some planes do fly within the bottom of the stratosphere to avoid the turbulence of the jet stream in the troposphere.
The ozone layer is located in the stratosphere. Ozone is a molecule that is made up of three oxygen atoms. Ozone is important because it blocks harmful rays from the sun. To learn more about radiation from the Sun, click below.
Ozone absorbs the ultraviolet rays from the Sun and turns them into heat. More light is absorbed at the top of the stratosphere than the bottom, so the air at the top of the stratosphere is warmer than the air at the bottom.
Unlike the troposphere, the air in the stratosphere does not move and mix very much. This is because the air in the stratosphere gets warmer as you move up and away from the Earth. The air in the troposphere mixes because warm air rises and cool air falls. Since the air in the stratosphere gets warmer as you move higher, the air will not rise the way it does in the troposphere.
The mixing in the troposphere happens because warm air rises and cool air falls. In the stratosphere, the warmer air is already on top, so it has nowhere to rise. This means that the air does not move around as much in the stratosphere as the troposphere.
Even though there is very little air in the stratosphere, there is still life there. Scientists have found bacteria on the dust in the stratosphere, and some birds fly through the lower part of the stratosphere including Rüppell's vulture and bar-headed geese.
Scientists, and even students, have sent weather balloons up into the stratosphere to learn more about it. In 2012, Felix Baumgartner achieved the highest skydive ever when he jumped from a balloon in the stratosphere.