ENERGY FROM THE SUN

The movement of heat in the atmosphere causes temperatures to change, winds to blow, and rain to fall.

Nearly all the energy in Earth’s atmosphere comes from the sun.

The sun’s energy travels in electromagnetic waves, mostly as visible light and infrared radiation.

A small amount of the sun’s energy travels as ultraviolet radiation.

Visible light includes all of the colors that you see in a rainbow.

Different wavelengths result in the different colors that you see.

Red and orange light have the longest wavelengths.

Blue and violet light have the shortest wavelengths.

Infrared radiation has longer wavelengths than red light.

Infrared radiation is invisible, but it can be felt as heat.

Ultraviolet radiation has shorter wavelengths than violet light.

Too much ultraviolet radiation can cause sunburn, skin cancer, and eye damage.

ENERGY IN THE ATMOSPHERE

Before reaching Earth’s surface, sunlight must pass through the atmosphere.

Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface.

The rest passes through the atmosphere to the surface.

ENERGY AT EARTH'S SURFACE

Some of the sun’s energy reaches Earth’s surface and is reflected back into the atmosphere.

About half of the sun’s energy, however, is absorbed by the land and water and changed to heat.

When Earth’s surface is heated, it radiates most of the energy back into the atmosphere as infrared radiation.

Much of this infrared radiation cannot travel all the way through the atmosphere back into space.

Instead, it is absorbed and forms a “blanket” around Earth that holds heat in the atmosphere.

This process is known as the greenhouse effect and keeps Earth’s atmosphere at a temperature that is comfortable for most living things.