This week we talked about the atmosphere. There are a few layers of the atmosphere and they are classified by the temperature. The lowest layer is the troposphere which is 10 miles high at the equator and 4 miles high at the poles. As temperature decreases the altitude increases. The second layer is the stratosphere. This layer begins 6-8 miles above sea level and ends 31-34 miles above sea level. Unlike the troposphere in the stratosphere as the temperature increases the altitude increases. Jet powered airplanes can fly here but not propeller powered. The third layer is the mesosphere. This layer starts 31 miles above sea level and ends 50-53 miles above sea level. The average temperature is -120 degrees .This level is too high for jet powered airplanes and is too low for satellites. The fourth layer is the thermosphere. This layer starts 50 miles above sea level and ends 312-620 miles above sea level.