6.3 Atmosphere Notes - Answer Key
Energy from the sun is known as solar energy. Earth only receives a small amount of
the sun’s energy. This small amount powers the atmosphere, oceans, and the Earth’s
surface.
Energy reaches Earth by electromagnetic waves. These waves are classified by
wavelength. Most energy from solar radiation (sun’s energy) reaches Earth in one of three
forms: visible light, infrared light, and ultraviolet radiation.
Before the sun’s rays can reach Earth’s surface, they must pass through the
atmosphere. Some energy is absorbed within the atmosphere while some is reflected.
Clouds are good “mirrors” which reflect a large amount of the incoming solar energy.
About 30% (or 1/3) of all the sun’s energy is reflected back into space. Only about 20% is
used by the Earth’s atmosphere. That means the remaining portion, or about 50% (1/2) of the
sun’s energy goes into the surface of the Earth. Together, the clouds, the atmosphere, and
the surface of the Earth are factors in Earth’s solar energy budget.
When Earth’s surface is heated, some of the energy returns to
the atmosphere as infrared radiation. Not all of the heat can
make it back out into space. Much of it is absorbed by gases in
the air. The energy from the absorbed radiation heats the gases
in the air. These gases form a “blanket” around the Earth that
holds heat in the atmosphere. This causes the greenhouse
effect.