The stratosphere is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere.
In the aerospace context, the stratosphere is the layer of the Earth's atmosphere that lies above the troposphere (the layer closest to the Earth's surface) and below the mesosphere. It is typically considered to extend from an altitude of about 15 kilometers (50,000 feet) to about 50 kilometers (165,000 feet) above the Earth's surface. The temperature in the stratosphere increases with altitude, unlike the troposphere where temperature decreases with altitude.
One example of the use of the stratosphere in aerospace is in the operation of high-altitude aircraft and balloons. These types of aircraft and balloons are able to fly in the stratosphere, where there is less atmospheric drag and less turbulence, allowing them to fly faster and more efficiently.
Another example is the use of stratosphere in the field of Earth observation, as the stratosphere is above most of the clouds and air pollution, making it an ideal location for instruments and platforms to gather data about the Earth's climate and atmosphere.
Additionally, Stratosphere is also used for the launch of some high altitude balloons, that carry payloads such as scientific instruments, cameras, communication equipment and others.