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Infrared radiation (The earth’s temperature partially depends on the rates…
Infrared radiation
The earth’s temperature partially depends on the rates at which light radiation and infrared radiation are
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When earth's surface absorbs visible light and high frequency infrared radiation, the planet’s internal energy increases and the surface gets hotter.
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The Earth also radiates lower frequency infrared radiation. Some of this infrared radiation is transmitted through the atmosphere back out into space, and some is absorbed by greenhouse gases in the atmosphere.
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Black bodies
Although there are no known objects that perfectly absorb every radiation directed at it, there are some which are close to this and are called 'Black bodies'
Perfect black bodies are theoretical, if they exited it would have the following properties:
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An object that is good at absorbing radiation is also a good emitter, so a perfect black body would be the best possible emitter of radiation.
Stars are considered to be black bodies because they are very good emitters of most wavelengths in the electromagnetic spectrum. This suggests that stars also absorb most wavelengths.
Whilst there are a few wavelengths that stars do not absorb or emit, this figure is very low, so they can be treated as black bodies. Planets and black holes are also treated as nearly perfect black bodies.
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