1 Urban Signatures: Thermal Radiation Big cities influence the environment around them. For example, urban areas are typically warmer than their surroundings. Cities are strikingly visible in computer models that simulate the Earth's land surface. This visualization shows outgoing thermal radiation predicted by the Land Information System (LIS) for a day in June 2001. Cities are warmer, so they emit more longwave (infrared) radiation. Only part of the global computation is shown, focusing on the highly urbanized northeast corridor in the United States, including the cities of Boston, New York, Philadelphia, Baltimore, and Washington. Still Image (1000x1000) This image shows outgoing thermal radiation (watts per square meter) predicted by LIS for 2001/06/11. The urban areas stand out very distinctly against their less radiative surroundings. 1 1 http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003155/cityThermal.png 34.5 44.5 -79.7 -69.7 Legend 1 3 http://svs.gsfc.nasa.gov/vis/a000000/a003100/a003155/thermal_bar.png