Infrared radiation in the spectral distribution of a black body is usually considered a form of heat, since it has an equivalent temperature, and is associated with an entropy change per unit of thermal energy.

Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere.

Infrared ( IR ) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 0. 74 micrometres ( µm ) to 300 µm.

Infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation.

Infrared ( IR ) light is electromagnetic radiation with a wavelength between 0. 7 and 300 micrometers, which equates to a frequency range between approximately 1 and 430 THz.

Infrared or red radiation from a common household radiator or electric heater is an example of thermal radiation, as is the heat and light ( IR and visible EM waves ) emitted by a glowing incandescent light bulb.

The Infrared Astronomical Satellite ( IRAS ) discovered an excess of infrared radiation coming from the star, and this was attributed to energy emitted by the orbiting dust as it was heated by the star.

Infrared astronomy is the branch of astronomy and astrophysics that studies astronomical objects visible in infrared ( IR ) radiation.

Infrared falls in between visible radiation, which ranges from 380 to 750 nanometers, and submillimeter waves.

Infrared radiation with wavelengths just longer than visible light, known as near-infrared, behaves in a very similar way to visible light, and can be detected using similar solid state devices.

* Infrared and radiation pyrometers

Infrared radiation from a specific range of wavelengths strikes the vanadium oxide and changes its electrical resistance.

* Infrared, a portion of the electromagnetic radiation spectrum

Infrared energy is just one part of the electromagnetic spectrum, which encompasses radiation from gamma rays, x-rays, ultra violet, a thin region of visible light, infrared, terahertz waves, microwaves, and radio waves.

* Infrared astronomy studies radiation with a wavelength that is too long to be visible to the naked eye but is shorter than radio waves.

Such cameras are often tuned for non-visible radiation for Infrared photography ( for night vision and heat sensing ) or X-ray ( for medical and video astronomy use ).

* Infrared astronomy deals with the detection and analysis of infrared radiation ( this typically refers to wavelengths longer than the detection limit of silicon solid-state detectors, about 1 μm wavelength ).

* Near Infrared, infrared radiation of a wavelength near that of red

Infrared homing refers to a passive missile guidance system which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track it.

; HIFI ( Heterodyne Instrument for the Far Infrared ): A heterodyne detector which is able to electronically separate radiation of different wavelengths, giving a spectral resolution as high as R = 10 < sup > 7 </ sup >.

Infrared homing refers to a passive missile guidance system which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track and follow it.

* Infrared vision, a capability of detecting infrared radiation

* Infrared radiation does not travel through common glass windows and therefore microbolometers can not be used to produce images if they are behind a standard glass window and objects and details behind glass cannot be seen.

Satellite measurements made in 1999 with the Wide Field Infrared Explorer showed that the brightness of Altair fluctuates slightly, varying by less than a thousandth of a magnitude.

Infrared EMR interacts with dipoles present in single molecules, which change as atoms vibrate at the ends of a single chemical bond.

Infrared spectroscopy ( IR spectroscopy ) is the spectroscopy that deals with the infrared region of the electromagnetic spectrum, that is light with a longer wavelength and lower frequency than visible light.

Infrared and terahertz-wave cameras are capable of creating images through clothing, though these images differ from what would be created with visible light.

A closeup of the Indian Nag Missile head, with the Imaging Infrared ( IIR ) Seeker

The Infrared Space Observatory was in a highly-elliptical geosynchronous orbit with an orbital height of apogee 70, 600 km and perigee 1, 000 km.

In some areas, emergency responders are provided with specialized equipment, such as an Mobile Infrared Transmitter, which allows emergency response vehicles, particularly fire fighting apparatus, to have high-priority travel by having the lights along their route change to green.

Infrared telescopes, which includes most major optical telescopes as well as a few dedicated infrared telescopes, need to be chilled with liquid nitrogen and shielded from warm objects.

Image: HAWK-I Messier 100. jpg | Infrared light with the HAWK-I camera on ESO's Very Large Telescope.

Infrared light, rather than visible light is used more commonly, because optical fibers transmit infrared wavelengths with less attenuation and dispersion.

; Multi-Object Infrared Camera and Spectrograph ( MOIRCS ): Wide-field camera and spectrograph with the ability to take spectra of multiple objects simultaneously, mounts on the Cassegrain focus.

; Infrared Camera and Spectrograph ( IRCS ): Used in conjunction with the new 188-element adaptive optics unit ( AO188 ), mounted at the infrared Nasmyth focus.

; Cooled Mid Infrared Camera and Spectrometer ( COMICS ): Mid-infrared camera and spectrometer with the ability to study cool interstellar dust, mounts on the Cassegrain focus.

; NIRC-2: The second generation Near Infrared Camera works with the Keck Adaptive Optics system to produce the highest-resolution ground-based images and spectroscopy in the 1 – 5 micrometers ( µm ) range.

; OSIRIS: The OH-Suppressing Infrared Imaging Spectrograph is a near-infrared spectrograph for use with the Keck II adaptive optics system.

Infrared satellite imagery can be used effectively for tropical cyclones with a visible eye pattern, using the Dvorak technique, where the difference between the temperature of the warm eye and the surrounding cold cloud tops can be used to determine its intensity ( colder cloud tops generally indicate a more intense storm ).

* Visualizing Chemistry with Infrared Imaging

In contrast, to detect a passively guided Infrared homing missile requires MAWS detectors with significant disadvantages: radar-based closure-detecting style MAWS radiate an easily-detectable signal which both reveals the aircraft and may be used as an auxiliary homing signal by AA missiles, and Infrared launch signature detector-based MAWS tend to be subject to a high false alarm rate which reduces attention paid them by the pilot.

Infrared connection was introduced with the Plus / Connection, but the Japanese Chou Jinsei Enjoy Tamagotchi was the first model to interact with a computer.