How does Infrared Heat Work?

Adam Hill
Adam Hill
Stealth aircraft like the F-22 Raptor are designed to have a low infrared signature.
Stealth aircraft like the F-22 Raptor are designed to have a low infrared signature.

Infrared refers to the wavelengths of the electromagnetic spectrum that lie between visible light and microwaves. Infrared radiation is perceived by us as heat, although we can’t see it. The origin of infrared heat is at the atomic level, where the heat generated by the movement of subatomic particles is changed into electromagnetic radiation in the infrared range. Infrared heat should be distinguished from thermal convection and thermal conduction, because it can travel through a vacuum.

Heat-seeking missiles, such as the AIM-9 Sidewinder, are designed to track the infrared heat emitted by a targeted aircraft's engines.
Heat-seeking missiles, such as the AIM-9 Sidewinder, are designed to track the infrared heat emitted by a targeted aircraft's engines.

To observe how infrared heat works, the heating and cooling of the earth is probably the most helpful example. Apart from driving all weather events and patterns, as well as ocean currents, infrared heat from the sun is what warms the Earth during the day, and it is what the ground gives off at night after the sun sets. It is interesting to note that while the sun does emit a huge amount of infrared heat, only about half of the heat we feel on the ground is from direct infrared radiation from the sun. The other half comes from energy from visible light that is absorbed by objects on earth, and then emitted later as infrared heat.

Infrared lies on the electromagnetic spectrium between visible light and microwaves.
Infrared lies on the electromagnetic spectrium between visible light and microwaves.

Man-made infrared heat is used in a variety of applications. In industrial contexts, the heating and welding of plastic is accomplished by infrared heaters, as is the curing of certain coatings, and certain steps in glass production. Many of us have seen infrared heat lamps in restaurants, which are used to keep food warm before it is served. These are specially designed light bulbs that are made to give off as much infrared energy as possible, with less emphasis on producing light.

Infrared emitters are used to transmit heat in saunas.
Infrared emitters are used to transmit heat in saunas.

Infrared heat can also be deliberately produced in such a way as to have a medically therapeutic effect. Far infrared radiation is sometimes used to provide pain relief to arthritis patients and others who suffer from chronic pain. It is also employed to de-ice aircraft wings, and in infrared saunas.

Not all infrared wavelengths are felt by us as heat. Light that is just beyond the red side of the visible spectrum is not hot at all, and this is the type of infrared light that is used by remote controls and some computing devices to transmit data. This part of the infrared range is called near infrared, because it is near the visible spectrum. Mid and far infrared waves are those that we notice as caloric heat.

Discussion Comments

anon254574

How would bio-mass react in a 'vacuum chamber' where far infrared rays are being emitted at a temperature above 1,700 degrees without combustion going on.

anon236035

This article seems to be perpetuating the myth that infrared radiation is "heat waves". It has no more heating ability than any other type of EM radiation. This misunderstanding probably comes from the fact that IR is emitted by all warm bodies ("warm" meaning above absolute zero).

Only about 50 percent of the warmth we feel from the sun is due to IR. The other 50 percent is mostly visible and UV.

The statement that "Not all infrared wavelengths are felt by us as heat" is flat out wrong. We don't feel heat from a remote control because the remote emits very little energy. It has nothing to do with the wavelength.

anon162226

We have used an infrared heater now for one season and really like the heat. It has saved us enormously on our oil fuel bills. However, we are noticing that the our hardwood floors have really been drying out. Is this typical? We don't know if it is just a new house drying out or if it is the effect of the infrared heat. Please advise.

healthnwell

@jenny1--I have found that I don't need to where any eye protection for the red infrared. Closing my eyes is fine.

If you use the near infrared, then it would be best to use goggles, metal is best. You might be able to find some goggles made from recyclable material as well.

jenny1

Is eye protection necessary from the effects of a far infrared healing lamp used on the facial area and, if so, what is the best type of eye protection to use?

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    • Stealth aircraft like the F-22 Raptor are designed to have a low infrared signature.
      By: dreamnikon
      Stealth aircraft like the F-22 Raptor are designed to have a low infrared signature.
    • Heat-seeking missiles, such as the AIM-9 Sidewinder, are designed to track the infrared heat emitted by a targeted aircraft's engines.
      By: McCarthys_PhotoWorks
      Heat-seeking missiles, such as the AIM-9 Sidewinder, are designed to track the infrared heat emitted by a targeted aircraft's engines.
    • Infrared lies on the electromagnetic spectrium between visible light and microwaves.
      By: designua
      Infrared lies on the electromagnetic spectrium between visible light and microwaves.
    • Infrared emitters are used to transmit heat in saunas.
      By: .shock
      Infrared emitters are used to transmit heat in saunas.