The animation will play through once automatically. To replay, click the play button. To step through frames individually, use the left and right arrows on the bottom right corner of the animation box or the left and right arrows on your keyboard. Background: A portion of the sunlight that enters the Earth system is reflected back into space, while the remaining portion of the sunlight is absorbed by the Earth system and stored as heat; some is absorbed in the atmosphere and some is absorbed in the lands and oceans. A percentage of this stored heat is emitted by the Earth system back into space in the form of longwave energy. The term “outgoing longwave radiation” refers to the sum total of all the longwave electromagnetic energy, or infrared radiation at wavelengths ranging from 5 to 100 micrometers, that escapes from the top of the Earth’s atmosphere back into space. The image above is a false-color map showing the amount of longwave energy (in Watts per square meter) that was emitted by the Earth system for the given month(s). In the image, the brighter yellow and orange regions show where more heat is emitted, while purple and blue regions show intermediate values, and white regions are lower values. Notice that most heat is escaping from the world’s equatorial and desert regions. Notice also the tropical heat transported northeastward by the Gulf Stream in the Atlantic Ocean. (Data courtesy ERBE Project, NASA LaRC) Cloud fraction represents the portion of sky in each pixel that is covered by clouds. Satellites can measure cloud fraction over the entire atmosphere and for all types of clouds. Since most clouds reflect incoming sunlight very well and trap heat escaping from the Earth’s surface, cloud fraction is an important parameter in studies of our planet’s radiant energy budget. (Data from International Satellite Cloud Climatology Project [ISCCP]). Questions: Discuss some of the patterns you see in the animation.     Focus on the Amazon. We know that the Amazon has high surface temperatures. Explain why the outgoing heat radiation is low.     As you know, the Amazon is a rainforest. Apply the data set and the animation you have just seen to define the characteristics of a rainforest.     Links: Clouds and Radiation (http://Earthobservatory.nasa.gov/Library/Clouds/)   Outgoing Heat Radiation (http://Earthobservatory.nasa.gov/Observatory/Datasets/lwflux.erbe.html)   On a Clear Day (http://Earthobservatory.nasa.gov/Study/ClearDay/)   Blanket of Clouds (http://Earthobservatory.nasa.gov/Study/BlanketClouds/)   next activity (#10): Comparing 4 Km2 fires during the month of August 1999 to fires in the month of February 2000 previous activity (#8): Comparing vegetation to surface temperature during the period from August 1985 to December 1992

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