This animation showing snow cover and sea ice surface temperature in the Northern Hemisphere portrays data collected from daily MODIS satellite images acquired during the winter of 2002-2003. Darkness increases with the onset of autumn, reaching a maximum at the Winter Solstice on December 21st. Thereafter, the circle of darkness shrinks as the period of daylight increases. Daily changes in sea ice are shown as ice surface temperature, which is related to the air temperature and the concentration of the sea ice. Sea ice surface temperatures range from about -40 to -2 degrees Celsius. Here, ice surface temperatures are depicted by colors, described by a color bar shown below. The snow tracks of several winter storms across the United States can be clearly seen. With an albedo of up to 80 percent or more, snow-covered terrain reflects most of the incoming solar radiation back into space, cooling the lower atmosphere. When snow cover melts, the albedo drops suddenly to less than about 30 percent, allowing the ground to absorb more solar radiation, heating the Earth's surface and lower atmosphere. Rapid changes in albedo, resultingfrom snowfall and snow melt, cause significant changes in the regional energy balance. This animation was accepted into the prestigious 2005 SIGGRAPH Electronic Theater, where it was shown during the annual conference from July 31 through August 4, 2005 in Los Angeles, CA. For more information on the data sets used in this visualization, visit NASA's
EOS DAAC website.