The sun gives off a lot of energy. Because the earth is round, the middle of the earth gets more energy than the top or the bottom.

When the North Pole is tilted toward the sun, it is summer for the top half of the earth. When the North Pole is tilted away from the sun, it is winter for the top half of the earth.

When the sun's energy gets to the earth's atmosphere, it is called radiation. Radiation delivers the energy in waves.

Only a small amount of the sun's energy actually reaches the earth's surface. This energy then heats the earth. Heat from the earth rises and helps heat up the atmosphere. This is called convection.

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Last modified: Fri Jun 13 13:21:31 PDT 1997