The stratosphere extends from the tropopause to approximately 50 kilometers. The lower part of the stratosphere interacts with the tropopause. In this part, strong winds blow in a circular motion and well defined channels, or layers horizontally around the earth. These winds are know as jet streams. The turbulent winds which blow in a circular motion are formed by friction and the dynamic interaction at the boundary between fast-moving and slow-moving air.
The stratosphere also contains the ozone layer which protects all living things on earth by shielding them from harmful forms of radiation that comes from the sun. Ozone is a pale blue gas that is composed of three oxygen atoms combined together. High concentrations of ozone can be poisonous to all living things. Near the earth’s surface ozone can act as a pollutant in the air.
Ozone in the upper layer of the stratosphere is also responsible for the temperature increase in this area because it has the ability to absorb radiant energy. Radiant energy is the energy that moves in waves, such as visible, invisible light and ultraviolet radiation. If the ozone gas did not absorb most of the radiant energy, our skin would burn and we would loose our eyesight or vision. The small amounts of ultraviolet radiation that reach the earth’s surface causes sunburn and suntans. Too much ultraviolet energy may cause skin cancer.
The temperatures in the lower part of the stratosphere remain constant, while the temperatures in the upper part increase as one moves away from the earth’s surface. The place where the temperature is the highest is called the stratopause. The stratopause separates the stratosphere from the next layer of the atmosphere.