Composition

• Earth's atmosphere is comprised mainly of just two gases. 78 percent of it is made up from nitrogen gas while another 21 percent is oxygen. Other gases in minute trace amounts such as argon, carbon dioxide and ozone also are in the atmosphere.
  
  

Troposphere

• The layer closest to Earth is called the troposphere. It is easily the thickest layer of the atmosphere and has a wildly varying temperature at the Earth's surface as compared to its top levels---a range averaging from 60 degrees Fahrenheit to minus 71 degrees.
  
  

Stratosphere

• The next layer above the troposphere is called the stratosphere; it extends 31 miles into space. The stratosphere is drier and not as dense as the troposphere and is actually warmer due to ultraviolet radiation absorbed by the ozone present in it.
  
  

Mesosphere

• After the stratosphere, the next atmospheric layer is known as the mesosphere. 53 miles high, the mesosphere is extremely cold, with temperatures as low as minus 135 degrees, and this is the region of the atmosphere where most meteors collide with air particles and burn up.
  
  

Thermosphere

• By far the largest layer of Earth's atmosphere is the thermosphere, which is 372 miles in height. In this layer, the air is very thin and is heated by the radiation generated by the Sun, making it possible for temperatures to reach as incredibly high as 3,000 degrees Fahrenheit. The thermosphere is the highest layer and eventually turns into outer space.