Infrared satellite images are used by meteorologists to determine where clouds are, but more importantly, how the clouds are moving. The infrared, IR, satellites work by measuring the infrared radiation that is emitted. Because the emitted radiation is proportional to temperature, the data are converted to temperature values, which can be useful for meteorologists. In comparison to clouds, the Earth's surface, even on very cold nights, is warm. When there are clouds, they absorb the radiation emitted by the Earth below and emit their own radiation at a much cooler temperature. Any area that has clouds shows up cooler than the ground, allowing meteorologists to detect the locations of the clouds. The height of clouds is inversely proportional to temperature, meaning that the tallest clouds are the coldest. It is often the tallest clouds that bring the most severe weather.
The satellites that collect these data are geostationary, meaning that they rotate at the same rate as the Earth so that the satellites are over the same spot
on Earth all the time. This allows them to collect a continuous stream of data for one location so that "movies" of the data can be made. Over the United States there
are two such satellites, the GOES (Geostationary Operational Environmental Satellites) -East and GOES-West. World wide there are many such satellites. This dataset is a
composite of GOES, Meteosat, and MTSat satellite data. Meteosat and MTSat are similar to GOES, but are operated by other countries. This real-time, color enhanced dataset is
shaded so that the significant clouds are brightly colored in order to stand out from the surface. The lowest clouds are white, medium level clouds are
shades of purple, and the highest clouds are teal. The background of this image is the "Blue Marble." The data is consistently updated so that the past thirty days
of data are available. In addition to this dataset, Real-time: Infrared Satellite over Land, illustrates the real-time location and movement of clouds based on data gathered by the GOES, Meteosat, and MTSat satellite data.