Saturday, May 25, 2013
WHAT IS GREENHOUSE EFFECT
Posted by
Green Yatra
at
7:38 PM
There are two meanings of the term "greenhouse effect". There
is a "natural" greenhouse effect that keeps the Earth's climate warm
and habitable. There is also the "man-made" greenhouse effect, which
is the enhancement of Earth's natural greenhouse effect by the addition of
greenhouse gases from the burning of fossil fuels (mainly petroleum, coal, and
natural gas). In order to understand how the greenhouse effect operates, we
need to first understand "infrared radiation". Greenhouse gases
trap some of the infrared radiation that escapes from the Earth, making the
Earth warmer that it would otherwise be. You can think of greenhouse gases as
sort of a "blanket" for infrared radiation-- it keeps the lower
layers of the atmosphere warmer, and the upper layers colder, than if the
greenhouse gases were not there.
About 80-90% of the Earth's natural greenhouse effect is due to water
vapor, a strong greenhouse gas. The remainder is due to carbon dioxide,
methane, and a few other minor gases.
It is the carbon
dioxide concentration that is increasing, due to the burning of fossil fuels
(as well as from some rainforest burning). This is the man-made portion of the
greenhouse effect, and it is believed by many scientists to be responsible for
the global warming of the last 150 years. Also, the concentration of
methane, although small, has also increased in recent decades. The reasons for
this increase, though, are uncertain.
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