Essential Knowledge

Earth’s atmosphere is divided into several different atmospheric layers extending from Earth’s surface outward. The air pressure, the force exerted by the gases pushing on an object, is greatest near the surface of Earth, in the troposphere. As altitude increases the gravitational pull decreases which results in a decrease in air pressure. The two most abundant (common) gases in all the layers of the atmosphere are nitrogen and oxygen. However, trace gases (such as argon) play an insignificant role in the layers. The atmosphere is divided into layers based on whether the temperature in the layer increases or decreases.

Troposphere:

• weather and clouds occur in this layer

• water vapor and carbon dioxide are also found in this layer and are important in the weather conditions in the layer

• as altitude increases temperature decreases

• extends from the surface of the earth up to 6-20 km high

Stratosphere:

• where the ozone layer is contained

ozone is a form of oxygen that is found in this layer

• cold except in its upper region where ozone is located

• extends from 20 km up to 50 km

Mesosphere:

• the coldest layer

• extends from 50 km up to 85 km

Thermosphere:

• the warmest layer

• the air is very thin in this layer

• extends from 86km up to 690km

Exosphere:

• cold regions of outer space extend from this layer

• extends from 691 km up to 10,000 km