31.   The sun does not heat the atmosphere directly since the envelope of air is mainly transparent to its high-energy radiation.

32.   The sun does not heat the atmosphere directly because the envelope of air is mainly transparent to its high-energy radiation.

33.   Thunderstorms develop from updrafts of humid air that are produced when the sun heats the ground.

34.   To know how to use shading effectively, it is helpful to understand how the summer sun heats your house.