18.12 The Greenhouse Effect
As we have seen, land and water absorb most of the sun's energy that reaches the earth after it passes through the atmosphere. But the earth then indirectly warms the atmosphere through the greenhouse effect. The shorter wavelengths of light strike the ground after passing through the clear atmosphere, just like light passing through the glass of a greenhouse. The warmed earth changes the shorter-wave solar energy to longer-wave infrared energy. The infrared energy radiates back toward space, and the lower atmosphere traps and absorbs much of this energy This is very similar to what happens in a greenhouse. Certain gases that make up the atmosphere, mainly water vapor and carbon dioxide, contribute most to absorbing heat These kinds of gases are called greenhouse gases.
The atmosphere helps Earth's inhabitants in more ways than just providing oxygen. Assuming we could even live without an atmosphere, we would be scorched in the daytime by the sun's full radiation. At night, the earth's temperature would drop far below freezing, just like it does on other planets. On the other hand, if the atmosphere absorbed all the sun's energy, none of it would get to us. Think of it—no sunny days! God's love of beauty and of His creatures has provided us with an atmosphere that is just right for life.
But we need to keep it that way. We need to create models that help us understand the atmosphere and protect its features. This is not easy. God made the earth, its atmosphere, and its processes complex. There's lots to do, but we have seen some success. Cities such as Los Angeles and Mexico City, that had been plagued with smog, now benefit from cleaner air because of atmospheric modeling.