Greenhouse Effect

The ability of Human activity destroy natural is weak in ancient time. It can only cause microclimate changes in a few areas at that time. Therefore between man and nature can live in peace for millions of years. However, since the Industrial Revolution it has a big change. Industrialization means burning amount of coal and oil, meanwhile emissions of exhaust gases to the Earth's atmospheric. Wherein the atmospheric greenhouse effect caused by carbon dioxide, it makes global warming, polar ice melting and sea levels rising; SO2 and nitrogen oxides can form acid rain; chlorofluorocarbon can damage the high-altitude ozone layer, causing the Antarctic ozone hole and global ozone thinning. In addition, the polluting gases by industrial emissions makes human settlements city became an island with high concentration air pollution. With the development of the economy and the improvement of life quality, the human also get into a big trouble. Many disasters appear to be a natural disaster, but in fact belong to man-made disaster and caused by man himself. The broken Earth's atmosphere is terrible revenge on human beings, because nature will never forgive the ignorance of mankind.

Since the industrial revolution, human burning a large number of fossil fuels and destroy forest make the carbon dioxide (CO2) content in global atmospheric increased by 25% in a hundred years. With the increase rate of CO2 at present, concentration of CO2 in atmosphere will double by 2100. According to the UN assessment report, the average global temperature will rise 1.0 ~ 3.5 ℃ compare to today, which will cause polar ice melting, sea levels rising 15 to 95cm, and then flooding large areas and thus developed coastal areas and other serious problems. Governments of various countries began to pay attention to this situation and its harmful consequences, discuss reducing CO2 emissions together.

What is the greenhouse effect?

The average global surface temperature is about 15 ℃. If there is no atmosphere cover, according to the principle that amounts of earth required solar heat is equal to Earth released to space, you can calculate the Earth's surface with an average annual temperature of -18 ℃. The 33 ℃ temperature is difference to protection from atmosphere. This is the greenhouse effect.

Any object in the universe radiates electromagnetic waves. The object with higher temperature, the shorter the wavelength it is radiation. The sun's surface temperature is about 6000K and electromagnetic waves it very short, called solar shortwave radiation (including visible light from violet to red). In an interview with the ground accept solar radiation and become warming, but also radiate electromagnetic waves to cool down at the same time. Due to the lower temperature of Electromagnetic waves emitted by the Earth, it has a longer wavelength, known as ground long wave radiation. Shortwave radiation and long wave radiation are different when passes through Earth's atmosphere. The atmosphere for solar radiation is almost transparent, and it strongly absorbs long-wave terrestrial radiation. At the same time of atmosphere i absorb long-wave radiation on the ground, which itself also radiates longer wavelength long wave radiation (because atmospheric temperature lower than the ground).   Wherein the radiation gets to the ground is called inverse radiation. After accepting the radiation the ground will heat up, it can be said that the atmosphere played a role of thermal insulation for the ground. This is the principle of the atmospheric greenhouse effect.

The insulation effect of Earth's atmosphere is similar to the top glass of flower conservatory, because the glass also has a shortwave solar radiation and absorption through the insulation function of terrestrial long wave radiation.

Greenhouse effect from greenhouse gases

We know that not every kind of gas in the atmosphere can strongly absorb long-wave radiation from ground. The Gas play the role of greenhouse acting from the Earth's atmosphere called the greenhouse effect, mainly carbon dioxide, methane, ozone, nitrous oxide, Freon and water vapor. They absorb almost all wavelengths radiation emitted by the ground, only a very narrow section absorb a little, this section is called "blind spot." Earth mainly through the blind spot return 70% the heat from the sun to space in the form of long-wave radiation, so as to maintain constant ground temperature. the greenhouse effect is mainly refers to the increase greenhouse gases by human activities, so that the thermal value form blind spots can below 70% and let the remaining thermal increase so that cause Earth warming.

However, CO2 and other greenhouse gases have strong ability to absorb long-wave radiation from ground, but they are rarely in the atmosphere. If in a standard state of both pressure of atmosphere and temperature are 0 ℃ , and then compressed the entire Earth's atmosphere to the standard state, it has a thickness of 8000 m. Current atmospheric CO2 content is 355(ppm is one millionth) and then converted it to the standard state is 2.8 m thick. In 8000 m thick atmosphere and just accounted for 2.8 m thick. Methane content is 1.7ppm, corresponding to 1.4 cm thick. Ozone concentration is 400ppb (ppb is one thousandth of ppm) conversion is only 3 mm thick. Nitrous oxide is 310ppb, 2.5 mm. There are many kinds of Freon, but most abundant in the atmosphere of Freon 12 has only 400ppt (ppt is one thousandth of ppb), converted to the standard state only 3 microns. This shows that the greenhouse gases are minimal in atmospheric concentrations. Because of this, without limit of anthropogenic emissions of greenhouse gases, can easily lead to global warming rapidly.