What is Greenhouse Effect?

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 green- house gases werenot 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.

Interesting facts:

DOES THE GREENHOUSE EFFECT EVEN EXIST?The greenhouse warming of the Earth's surface is believed by some people to be physically impossible. They claim it would violate the 2nd Law of Thermodynamics, which basically states that energy must flow from where there is more to where there is less. The reason for this apparent violation is that the existence of greenhouse gases in the COLDER layers of the atmosphere make the surface WARMER, which would suggest energy flow from colder to warmer, which would seem to violate the 2nd Law. But the greenhouse effect is kind of like adding a lid to cover a pot of water on the stove...even though the lid is colder than the water, its presence actually makes the water warmer. It's the TOTAL (net) flow of energy which must be from warmer to colder, which is indeed the case in both the greenhouse effect, and adding a lid to the pot of water on the stove. With global warming still in the fore and still a big issue, a lot of people are still uninformed properly about it! A lot of places are getting warm, forcing quite a number of people to head off to the beach or fan  themselves endlessly. Many are still under the assumption  that greenhouse gases, which contribute to making the planet warm, should really go. What they don’t know is that the primary purpose of those gases is to prevent heat from escaping into space, preventing  the world from turning into one huge snowball! If they didn’t exist,  we wouldn’t be able to live on this planet. This little article will tell you about the most powerful greenhouse gases in the world. Some may even surprise you.  1. Water vapor – Yes. Water. Right on top of the list. Water vapor contributes from 36% to 66% of the world’s greenhouse effect. It’s also the most abundant greenhouse gas! Concentrations of water vapor fluctuate throughout the world, and humans don’t affect  it directly on a large scale. In addition, warm air caused by the greenhouse effect can carry more water vapor, amplifying the greenhouse effect further. However, humidity is constant. The  net effect is overall positive, and also protects against the excess carbon dioxide. 2. Carbon Dioxide – Ah, the gas that many people blame for heating up the earth. It contributes 9% to 26% of the greenhouse effect depending on area. The world’s species and environmental cycles produce this gas naturally, up to twenty times that of what we  contribute! Nature cycles the carbon dioxide through plants and weathering, but human production has speeded it up more than nature can account for. Majority of manmade carbon dioxide  comes from burning fossil fuels and deforestation. 3. Methane – This gas causes 4% to 9% of the greenhouse effect. Human methane production mostly comes from livestock. By itself, it is an effective greenhouse gas, but it can transforms to water and carbon dioxide in the atmosphere, which makes it quite  effective in warming the earth! If that isn’t enough, it also turns into ozone, which is another greenhouse gas! This is why the  amount of methane around is has been more or less constant, and it is why its effect is considered small since many who measure it do not include what it turns into. 4. Ozone – This gas we all know and love as protector against the sun rays is also a greenhouse gas. It causes only 3% to 7% of the greenhouse effect. Ozone causes irritation to the respiratory  system at ground level, but is normally very light at that level, choosing  instead to concentrate higher up. However, the concentration of ozone at ground level is increasing, because of pollution! This is  especially concentrated in populated areas. It decays quickly to normal oxygen. Now that you know a little bit more about these gases, the question remains. What can we do? What we can, of course. How about you? What do you know about greenhouse gases? Well we'll talk dsiadvantages if greenhouse gases later first lets see about function of greenhouse and its uses. Function Greenhouses made of glass allow solar radiation into the building, but the warmth re-radiated by the plants and soil inside is emitted in the infrared portion of the light spectrum, a longer wavelength that is trapped inside by the glass. The resulting heat warms the air at the bottom of the greenhouse. This air rises to the glass ceiling and  remains inside. Cooler air replaces it near the ground and warms until it rises, starting the cycle over again. This is how the  temperature inside a greenhouse continues to climb and why ventilation is so important. Growing Flowers Greenhouse growing allows flower lovers to harvest early cuts before the blooming season, and winter cuts long after the outdoor summer annuals have given up for the year. The warm, moist conditions are ideal for tropical varieties like orchids, blood lilies and blue jacaranda, but they  also tend to breed pests and disease, so managing your flower crop  requires constant attention. Some of the more common afflictions facing greenhouse flowers are root rot, fungal infections and mildew. Pesticides, either organic or chemical, are a must but keeping weed growth under control both inside and  around the greenhouse can help to keep insect numbers down,  according to the University of Kentucky College of Agriculture’s new crop opportunity center. Growing Plants A greenhouse should be positioned so that it receives direct sunlight from the spring and fall sun when it is lower in the sky. Inside,  commercial potting soil works well for most large beds. Mixes should include sand, peat moss, vermiculite and fir bark to aid in soil drainage. There is no limit to the variety of plants you can grow in a greenhouse,  but mixing too many different types could present a problem in temperature management. Ventilation systems can be fully automatic and expensive, or decidedly low-tech. Spraying water on the floor and opening the ceiling vents is  one cheap way to reduce the temperature inside rather quickly. Growing Vegetables Root vegetables like turnips, carrots and beets do very well in greenhouses.  They can be kept in planter boxes and lined up around the perimeter  under work spaces and benches. Use tubs for tomatoes, beans, cucumbers and lettuce. Corn can take over a greenhouse, but the yield is terrific.  After this lets know about the greenhouse gases and its advantage and disadvantages: A greenhouse gas is one of several gases that can absorb and emit  longwave (infrared) radiation in a planetary atmosphere. This  phenomenon is often termed the greenhouse effect. Of the sunlight  that falls on the Earth's surface, approximately 40% of that energy  is reradiated upward into the atmosphere in the form of longwave radiation. Approximately 75% of that upward radiated longwave energy is absorbed by water vapor, carbon dioxide, methane and other greenhouse gases. Since this absorption process is molecular in nature,  the subsequent reradiation of energy by these gases is multidirectional. As a result, about 50% of the longwave emission is reradiated back  toward the Earth where it is once again turned into heat energy.  Through this process, greenhouse gases contribute to the amount of heat energy released at the Earth's surface and in the lower atmosphere. Since the beginning of Industrial Revolution, concentrations of carbon  dioxide, methane, and nitrous oxide have all risen dramatically  because of human activities. Fossil fuel combustion, land-use change, increasingly intensive agriculture, and an expanding global human  population are the primary causes for these increases. Other  greenhouse gases found in our planet's atmosphere include water  vapor, ozone, sulfur hexafluoride and chlorofluorocarbons. To look at the small animation of greenhous effect goto: http://www.climatechoices.org.uk/animation/greenhouse.swf