Thursday, July 7, 2011

Infrared Radiation


  • Infrared is the radiation important by the Earth's weather and climate.
(if not there would be global warming or global cooling)
  • Low power and cost requirements (to power electronic devices) 
  • Allows images to be produced at night (Night vision)
  • Are used to ionize gases which later are used for helpful purposes
  • Allows people to do Medical treatments

Greenhouse effect:

Greenhouse gases in the atmosphere, especially water vapor, absorb and emit some of this infrared radiation, and keep the earth habitably warm. Clouds also produce their own greenhouse effect. 

Water vapor (H2O) is the most active molecule in absorbing infrared radiation and thus in heating the atmosphere. It accounts for about 55% of the absorption of thermal radiation in the atmosphere.

Carbon dioxide (CO2) also absorbs infrared radiation and accounts for about 18%, methane (CH4) accounts for about 6% and ozone (O3) accounts for about 5% of heating the atmosphere.

Since some infrared radiation is lost into space, the recent percentages of carbon dioxide and methane in the atmosphere have allowed the temperature to remain stable.

CO2 has stayed at the proper percentage in the atmosphere until recently, when an increasing amount of the gas has been emitted due to the burning of fossil fuels. Automobile exhaust and industrial smoke contribute the most CO2.

The reason why the air cools so quickly on a clear, dry evening is because the lack of humidity and clouds allows large amounts of IR radiation to escape rapidly to outer space as it is emitted upward by the ground and other surfaces.


Line of sight: transmitters and receivers must be almost directly aligned (i.e. able to see each other) to communicate 

Blocked by common materials: people, walls, plants, etc. can block transmission 

Short range: performance drops off with longer distances 

Light, weather sensitive: direct sunlight, rain, fog, dust, pollution can affect transmission 

Speed: data rate transmission is lower than typical wired transmission

Bad effects of infrared:
Gradual Opacity of the Eye's Lens


 We cannot see infrared radiation, but we can feel it as heat energy. Infrared sensors can detect heat from the body. They are used in:

  • security lights
  • burglar alarms

Infrared radiation is also used to transmit information from place to place, including:

  • remote controls for television sets and DVD player
  • data links over short distances between computers or mobile phones
  • Photographers use film that is sensitive to infrared rays to take pictures in places where there is no visible light. Burglar alarms also use infrared.

Done by: Cherin, Benjamin, Si Yuan and Niklaus

1 comment:

  1. "Gradual Opacity of the Eye's Lens" What do you mean by this sentence? How does an eye's lens become opaque?