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       #Post#: 384--------------------------------------------------
       kerja 
       By: hafizhamid Date: March 1, 2011, 10:44 pm
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       The greenhouse effect is a process by which thermal radiation
       from a planetary surface is absorbed by atmospheric greenhouse
       gases, and is re-radiated in all directions. Since part of this
       re-radiation is back towards the surface, energy is transferred
       to the surface and the lower atmosphere. As a result, the
       temperature there is higher than it would be if direct heating
       by solar radiation were the only warming mechanism.[1][2]
       This mechanism is fundamentally different from that of an actual
       greenhouse, which works by isolating warm air inside the
       structure so that heat is not lost by convection.
       The greenhouse effect was discovered by Joseph Fourier in 1824,
       first reliably experimented on by John Tyndall in 1858, and
       first reported quantitatively by Svante Arrhenius in 1896.[3]
       If an ideal thermally conductive blackbody was the same distance
       from the Sun as the Earth is, it would have a temperature of
       about 5.3 °C. However, since the Earth reflects about 30%[4] (or
       28%[5]) of the incoming sunlight, the planet's effective
       temperature (the temperature of a blackbody that would emit the
       same amount of radiation) is about −18 or −19
       °C,[6][7] about 33°C below the actual surface temperature of
       about 14 °C or 15 °C.[8] The mechanism that produces this
       difference between the actual surface temperature and the
       effective temperature is due to the atmosphere and is known as
       the greenhouse effect.
       Global warming, a recent warming of the Earth's surface and
       lower atmosphere,[9] is believed to be the result of a
       strengthening of the greenhouse effect mostly due to
       human-produced increases in atmospheric greenhouse gases.
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