Incoming visible light (which passes relatively easily
through the atmosphere) is absorbed by the earth’s surface and re-
radiated as infrared (longer wavelength) radiations This radiation is
trapped by greenhouse gases such as carbon dioxide and water vapour Infrared detectors are used in Earth satellites, both for military purposes
and to observe growth of crops Electronic devices (for example
semiconductor light emitting diodes) also   emit infrared and are widely
used in the remote switches of household electronic systems such as TV
sets, video recorders and hi-fi systems