The image on the left below shows the average amount of incoming solar radiation that reaches Earth's surface each month. Greenish areas show where the amount of solar energy coming into Earth is greater than the amount of heat energy leaving the surface (a net gain of energy). Bluish areas are where there is less incoming energy than escaping heat energy (a net loss of energy).

The image on the right shows the average land and sea surface temperatures for each month. Reds and oranges indicate high temperatures, and blues and violets represent low temperatures.

  !   Click the image to view the movie. Play the animation several times. Observe the shifting horizontal bands in each animation.

2. What do you think causes the systematic shift of radiation and temperature bands through the year?

The width of different colored bands in the net radiation images remains fairly consistent through the year. The color bands in the surface temperature images change considerably. Not only do their widths change, "pockets" of different temperatures appear within the bands. On the following pages, you'll examine some of the factors that cause variations in temperature even for locations that receive similar amounts of solar radiation.