Infared radiation

• All objects emit infared radiation.
• Infared radiation is emit by the sun.
• Infared radiation are electromagnetic waves. Their wave lengths are longer than visible light.
• Infared radiation is experienced by heat and therefore is invisible.
• A perfect black body are the best absorbers of infared but are also the best emitters. The radiation emitted by the black body is called black body radiation.
• The higher the temperature of an objects, the more infared radiation it will emit. Objects/ bodies at a constant temperature will emit the same amount of radiation that they are absorbing.
• White coloured surfaces are the worst absorbers and emitters of infared radiation. This is why on a hot summer day, inside a white car will be cooler than in a black car.
• The shorter the wavelength of infared radiation, the greater the intensity of radiation.
• If an object is absorbing more radiation than it is emitting, then its temperature will increase. If an objects is emitting more radiation than it is absorbing, then its temperature will decrease.
• Shiny blankets are used to keep people warm. This works because shiny white surfaces emit less radiation than dark surfaces.
• Why is the earth warming up?

  Infared radiation is emitted by the sun.

  Some of this radiation is absorbed by the earth and some is emitted back out into the atmosphere.

  There are lots of greenhouse gases, like methane and carbon dioxide in the atmosphere.

  Greenhouse gases are very good at emitting Infared radiation.

  When the radiation is emitted by earth, some may hit a greenhouse gas.

  When this happens, the greenhouse gas will emit the infared in all directions and it will be absorbed by the earth again.