Average Total-sky Net Radiant 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 net radiant flux from July, 2002 through June, 2004 as measured by the CERES instrument. This is the incoming radiation minus the outgoing reflected or thermal energy given off by areas of the Earth. Regions in red and yellow have a net incoming flux and are being heated. Regions in blue have a net outgoing flux and are being cooled. Regions in black are in rough equilibrium. Cloud-free summertime oceans are heated the most, while high latitude winter regions are cooled the most, probably because of the longer winter nights. Note that regions that reflect a lot of sunlight, such as the polar ice sheets and the Sahara desert are almost always in equilibrium or are cooling regions.

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