This is a thermogram of a house, an IR view of a house. It shows variations in the amount of heat that escapes from a home. Greater heat loss appears in red. Blue indicates areas where little or no heat radiates from the building.
Click on image for full size
Daedalus Enterprises, Inc., Ann Arbor, MI
Infrared (IR) Radiation
Infrared (IR) radiation is a type of electromagnetic
radiation. Infrared "light" has a longer wavelength than visible
light. Red light has a longer wavelength than other colors of light, and
infrared has even longer waves than red does; so infrared is sort of "redder-than-red"
light or "beyond red" light. We cannot see infrared radiation, but we can sometimes
feel it as heat.
Infrared radiation lies between visible light and radio waves on the electromagnetic
spectrum. IR light has wavelengths between about 1 millimeter and 750
nanometers. The wavelength of red light is 700 nanometers (or 7,000 ┼).
Infrared radiation oscillates at rates between 300 gigahertz (GHz or 109 hertz)
and 400 terahertz (THz or 1012 hertz).
The infrared spectrum is sometimes subdivided into the far infrared (1 mm
to 10 Ám wavelengths), mid infrared (10 to 2.5 Ám wavelengths),
and near infrared (2,500 to 750 nm wavelengths). A portion of the far IR, including
wavelengths between 100 and 1,000 Ám, is sometimes referred to as the
extreme infrared. Boundaries aren't always distinct, and difference between
extreme IR radiation and microwave
radio frequencies is less than crystal clear.
We feel infrared radiation as heat. The heat our hand feels when placed above
a burner on an electric stovetop after the burner has been turned off (and
is no longer glowing red) but has not yet cooled is infrared radiation.
Earth's atmosphere is opaque to much of the infrared part of the spectrum.
Water vapor, carbon dioxide, methane, and other greenhouse
gases tend to absorb
IR radiation, trapping extra
heat in Earth's lower
Night vision goggles and TV remote controls both make use of infrared "light"
to accomplish their tasks.
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