Global Reflected Shortwave Solar Radiation

Notice which regions on this map reflect the sun’s energy back into space: The white or beige areas show sunlight reflecting from Africa’s Sahara Desert, as well as from high clouds over the tropical oceans, Amazonia, and tropical Africa. On the other hand, darker areas show sunlight penetrating the atmosphere in the cloud-free areas of the oceans.

This view illustrates the earth’s reflectivity, or albedo. The earth’s average albedo is about .3, which means that the earth reflects about 30% of the sunlight that hits it overall. However, different areas reflect different amounts of energy: Clouds, deserts, and snow have high albedos and reflect away most of the sunlight they receive; vegetation and water, with lower albedos, absorb more of that energy.

These processes form the earth’s energy budget—and they are key in determining climate: Sunlight that penetrates the atmosphere heats the earth’s surface. Some of that heat is trapped by the atmosphere, keeping the planet warm. That’s why studying the balance between absorption and reflection is a fundamental step in understanding climate.