<P> Light, or visible light, is a very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye, or 380--750 nm which equates to a frequency range of 790 to 400 THz respectively . More broadly, physicists use the term "light" to mean electromagnetic radiation of all wavelengths, whether visible or not . </P> <P> Infrared (IR) light is electromagnetic radiation with a wavelength between 0.7 and 300 micrometers, which corresponds to a frequency range between 430 and 1 THz respectively . IR wavelengths are longer than that of visible light, but shorter than that of microwaves . Infrared may be detected at a distance from the radiating objects by "feel ." Infrared sensing snakes can detect and focus infrared by use of a pinhole lens in their heads, called "pits". Bright sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level . Of this energy, 53% is infrared radiation, 44% is visible light, and 3% is ultraviolet radiation . </P> <P> Microwaves are electromagnetic waves with wavelengths ranging from as short as one millimeter to as long as one meter, which equates to a frequency range of 300 MHz to 300 GHz . This broad definition includes both UHF and EHF (millimeter waves), but various sources use different other limits . In all cases, microwaves include the entire super high frequency band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3mm). </P> <P> Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light . Like all other electromagnetic waves, they travel at the speed of light . Naturally occurring radio waves are made by lightning, or by certain astronomical objects . Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and innumerable other applications . In addition, almost any wire carrying alternating current will radiate some of the energy away as radio waves; these are mostly termed interference . Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may bend at the rate of the curvature of the Earth and may cover a part of the Earth very consistently, shorter waves travel around the world by multiple reflections off the ionosphere and the Earth . Much shorter wavelengths bend or reflect very little and travel along the line of sight . </P>

Types of radiation in order of their energy