The GOES satellite senses electromagnetic energy at five different wavelengths. There are two wavelengths most commonly shown on weather broadcasts: Infrared and Visible.
In the infrared (IR) channel, the satellite senses energy as heat. The earth’s surface absorbs about half of the incoming solar energy. Clouds and the atmosphere absorb a much smaller amount. The earth’s surface, clouds, and the atmosphere then re-emit part of this absorbed solar energy as heat. The infrared channel senses this re-emitted radiation. A major advantage of the IR channel is that it can sense energy at night, so this imagery is available 24 hours a day. This is a disadvantage of the visible channel, which requires daylight and cannot “see” after dark.