View source for Greenhouse effect

==Definition== 

Short-wave electromagnetic [[radiation]] from the [[Sun]] passes through the transparent atmosphere 
unhindered (except for the effect that [[albedo]] has on the mean reflectivity of a planet). On heating the planet's surface, long-wave radiation (i.e. Infrared radiation) is emitted into the atmosphere. Long-wave radiation will not escape into space if the [[atmosphere]] is dense enough, and contains [[greenhouse gases]] (such as [[carbon dioxide]], [[water]] vapour, [[methane]] etc.) which reflect long-wave radiation back to the surface, heating the atmosphere further. This shortwave input, long-wave emission, long-wave reflection, atmospheric heating process is known as the '''Greenhouse Effect'''. 

==[[Terraforming]] Mars== 

The Greenhouse Effect is an essential process to heat a planet's atmosphere to habitable temperatures. To make life sustainable on the surface of Mars, the process of [[:category:Terraforming Mars|terraforming]] would require a thickening of the tenuous Martian atmosphere and injection of selected [[greenhouse gases]]. Decreasing the planet's [[albedo]] would also be beneficial.

==Artificial Greenhouse Effect== 

[[greenhouse|Greenhouses]] are artificial structures that harness heating from the greenhouse effect. Greenhouses will be an essential addition to future colonies on Mars if they are to be [[Manned One-way Mission|long-term and self-sufficient]]. Essential for growing [[food]], greenhouses will also provide immense [[morale|feelings of well-being]] for [[humans]] living away from Earth, so the psychological effects on colonists will be invaluable. 

==Examples of the Greenhouse Effect== 

*[[Venus]] has a very dense atmosphere, causing a ''runaway'' greenhouse effect. Temperatures on Venus' surface are increased by 400 degrees by this extreme heating creating a surface temperature of over 700 Kelvin and surface pressure of 90 times that of the Earth's atmosphere (about 1350 pounds per square inch). 
*[[earth|Earth's]] [[global warming]] is believed to be in direct correlation with carbon emissions from industrial burning of [[fossil fuels]] and other human activity. It is believed the planet will reach a "tipping point" where the heating cannot be sustained by the atmosphere causing a catastrophic collapse in [[weather systems]] and climate shift. Now Earth greenhouse effect is 33ºK.
*[[mars|Mars]] [[global warming]] at present have very thin atmosphere producing only 6ºK<ref name=Making_Mars_habitable> Christopher P. McKay, Owen B. Toon & James F. Kasting - ''Making Mars habitable'', Nature 352, pp. 489-496. DOI:10.1038/352489a0</ref> greenhouse effect. 

==References==
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[[category:Terraforming Mars]] 
[[category:Climate]]