Global Climate Change The Exploratorium
home atmosphere hydrosphere cryosphere biosphere global effects
home
   

 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.


 glossary glossary terms  

Click for definitions of words used on this page:

albedo
electromagnetic radiation
energy budget
El Niño/Southern Oscillation
forcing
greenhouse effect
negative feedback
positive feedback

View the full, printable version of the glossary.


Latest Sea Surface Temperatures

Global Reflected Shortwave Solar Radiation - Shortwave radiation is visible light—in this case, sunlight. This satellite image shows sunlight reflected from the earth back into space. Green and blue areas show light penetrating the atmosphere; white and beige indicate areas where light reflects back into space. This picture was constructed from images gathered over a one-month period during March 2000. Source:CERES instrument team


 questions about the data  

question Would melting the polar ice caps or glaciers reduce the earth’s albedo? What effects could this have?

email Email your own questions about this data set. 

 research connection  

Active since February 2000, NASA’s Terra satellite system measures the energy that the earth receives from the sun and emits back into space. Technological innovations such as satellite imaging can radically change the way scientists work and even allow them to answer questions they could not resolve before. Before the 1970s, global images like this one did not exist, because satellite imaging of the earth was impossible.


 related sites  
Earth Observatory - NASA animation illustrating changes in reflected sunlight over time.

NASA’s Remote Sensing Tutorial - Thorough background on interpreting satellite images.
 

home | atmosphere | hydrosphere | cryosphere | biosphere | global effects

about this site - © 2002 The Exploratorium