Causes Of Greenhouse Effect

The Earth and Venus are near each other in the solar system, and are similar in size, density and composition. Based on our understanding of the origin of the solar system, we anticipate that their initial atmospheres would have been rather similar. However, the current atmosphere of both planets could hardly be more different than they are. How did it be? The reason is thought to lie in what is called the "runaway greenhouse effect.

The sunlight falling on the surface of a planet is mainly in the visible spectrum. However, the reflection of light from the surface tends to produce light with a wavelength called infrared (IR) (also known as radiant heat, infrared radiation is heat that we feel to be issued by a hot surface like a piece of hot metal).

Now, because of their molecular structures, certain gases like carbon dioxide and water vapor (and many others) have the property that they are essentially transparent to visible light but absorb infrared radiation strongly . These compounds are sometimes called greenhouse gases because, if they are present in a planetary atmosphere, they absorb infrared radiation dispersed and tend to raise the temperature of the atmosphere by trapping solar energy. (The analogy with an actual greenhouse is imperfect because the mechanism by which a greenhouse stays warm is different, but it is good enough that the name "(Planetary) Greenhouse Effect" is now common phenomenon .)

The greenhouse effect occurs for all planetary atmospheres containing greenhouse gas emissions, and is responsible for their being warmer than would otherwise be the case. The greenhouse effect by itself could not reflect the conditions found on Venus. However, under certain conditions, we believe the greenhouse effect can "escape". For example, consider the case of a planet like Earth. The Earth has enormous amounts of two greenhouse gases: water vapor and carbon dioxide. However, for the Earth over the water and carbon dioxide are not in the atmosphere. Water is most often in the oceans, and carbon dioxide is mostly bound chemically in rocks made from compounds that chemists call carbonates (eg limestone).

Suppose now that we have increased the efficiency of greenhouse heating of the atmosphere of the Earth, for example by increasing the amount of sunlight falling on it, or by increasing the concentration of greenhouse gases in the atmosphere (eg, burning fossil fuels, which produce water vapor and carbon dioxide as byproducts of combustion). We could then expect that the temperature rises into the atmosphere (assuming no other effects intervened --- a big "if" in the realistic case, because the atmosphere is complicated). This would be a greenhouse.

It would become a runaway greenhouse effect if the rising temperature approached the boiling point of water, because then the oceans would begin to convert to water vapor, water vapor could increase trapping efficiency of the heat and accelerate the greenhouse effect, this would cause the temperature to rise further, causing oceans to evaporate faster, etc., etc. (This type of drift is also called a loop "feedback encouraging. ") When the oceans were gone in the atmosphere would finally stabilize at a much higher temperature and at a much higher density, because all water would be in the atmosphere today.

We can look one step further on the run in this scenario. Suppose that the previous boom raised the temperature so high that chemical reactions begin to occur on this disc rocks carbon dioxide in the atmosphere (the process is called sublimation; few hundred degrees Celsius would be sufficient). Then another flight would occur in the power of carbon dioxide in the atmosphere would accelerate the heating, W.