Average Clear-sky Outgoing Longwave Flux (WMS)

The Earth's climate is determined by energy transfer from the sun to the Earth's land, oceans, and atmosphere. As the Earth rotates, the sun lights up only part of the Earth at a time, and some of that incoming solar energy is reflected and some is absorbed, depending on type of area it lights. The average amount of reflection and absorption is critical to the climate, because the absorbed energy heats up the Earth until it is radiated away as thermal radiation. This animation shows the monthly average clear-sky outgoing longwave radiation from July, 2002 through June, 2004 as measured by the CERES instrument. This is the thermal radiation given off by the warm Earth when the sky is cloud free. The Earth's rotation and the movement of warm air from the equator to the poles make the Earth roughly uniformin temperature. The most visible features are the cold poles in winter and the significant regions of snow coverage in the northern hemisphere, also in winter.

See http://asd-www.larc.nasa.gov/ceres/ASDceres.html