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لي إضافة بسيطة باللغة الإنجليزية:
The Greenhouse Effect
Introduction
The greenhouse effect refers to circumstances (الظروف) where the short wavelengths of visible light from the sun pass through a transparent medium and are absorbed, but the longer wavelengths of the infrared re-radiation from the heated objects are unable to pass through that medium. The trapping of the long wavelength radiation leads to more heating and a higher resultant temperature.
Besides the heating of an automobile by sunlight through the windshield and the namesake example of heating the greenhouse by sunlight passing through sealed, transparent windows, the greenhouse effect has been widely used to describe the trapping of excess heat by the rising concentration of carbon dioxide in the atmosphere. The carbon dioxide strongly absorbs infrared and does not allow "as much of" it to escape into space.
A major part of the efficiency of the heating of an actual greenhouse is the trapping of the air so that the energy is not lost by convection.
In other words
The greenhouse effect is the rise in temperature that the Earth experiences (تُقاسيه) because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Without these gases, heat would escape back into space and Earth’s average temperature would be colder.
Greenhouses work by trapping heat from the sun. The glass panels of the greenhouse let in light but keep heat from escaping. This causes the greenhouse to heat up, much like the inside of a car parked in sunlight, and keeps the plants warm enough to live in the winter. The Earth’s atmosphere is all around us. It is the air that we breathe.
Greenhouse gases in the atmosphere behave much like the glass panes in a greenhouse. Sunlight enters the Earth’s atmosphere, passing through the blanket of greenhouse gases. As it reaches the Earth’s surface, land, water, and biosphere absorb the sunlight’s energy. Once absorbed, this energy is sent back into the atmosphere. Some of the energy passes back into space, but much of it remains trapped in the atmosphere by the greenhouse gases, causing our world to heat up.
The greenhouse effect is important. Without the greenhouse effect, the Earth would not be warm enough for humans to live. But if the greenhouse effect becomes stronger, it could make the Earth warmer than usual. Even a little extra warming may cause problems for humans, plants, and animals. Greenhouses are used to grow plants, especially in the winter.
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Greenhouse Effect Example
Bright sunlight will effectively warm your car on a cold, clear day by the greenhouse effect. The longer infrared wavelengths radiated by sun-warmed objects do not pass readily through the glass. The entrapment of this energy warms the interior of the vehicle. The trapping of the hot air so that it cannot rise and lose the energy by convection also plays a major role.
Short wavelengths of visible light are readily transmitted through the transparent windshield.
Shorter wavelengths of ultraviolet light are largely blocked by glass since they have greater quantum energies which have absorption mechanisms in the glass. Even though you may be uncomfortably warm with bright sunlight streaming through, you will not be sunburned.
[flash=http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/greenhouse.swf]WIDTH=500 HEIGHT=500[/flash]
Increase in Greenhouse Gases
The increase in the concentration of carbon dioxide, one of the three major atmospheric contributers to the greenhouse effect, has been carefully ********ed at the Mauna Loa Observatory in Hawaii. The 1990 rate of increase was about 0.4% per year. The interesting cyclic variations represent the reduction in carbon dioxide by photosynthesis during the growing season in the northern hemisphere.
Current analysis suggests that the combustion of fossil fuels is a major contributer to the increase in the carbon dioxide concentration, such contributions being 2 to 5 times the effect of deforestation.
http://www.youtube.com/watch?v=5zLuq...layer_embedded
Contributers to Greenhouse Effect
Those gas molecules in the Earth’s atmosphere with three or more atoms are called "greenhouse gases" because they can capture outgoing infrared energy from the Earth, thereby warming the planet.
The greenhouse gases include:
Water vapor with three atoms (H2O),
Ozone (O3),
Nitrous Oxides (N2O)
Carbon dioxide (CO2), and
Methane (CH4).
Also, trace quantities of chloro-fluoro-carbons (CFC’s) can have a disproportionately large effect.
To attempt to quantify the effects of greenhouse gases on the global temperature, climatologists use the "radiative forcing" of the current atmospheric content of these gases.
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