سؤال قراءة ستيب محلول — فهم التفاصيل (تدريب 5628)

(1) The greenhouse effect is a naturally occurring process that aids in heating the Earth's surface and atmosphere. It results from the fact that certain atmospheric gases, such as carbon dioxide, water vapor, and methane, are able to change the energy balance of the planet by absorbing long wave radiation emitted from the Earth's surface. Without the greenhouse effect life on this planet would probably not exists, as the average temperature of the Earth would be a chilly-18 º Celsius, rather than the present 15 º. (2) As energy from the Sun passes through the atmosphere a number of things take place. A portion of the energy (26% globally) is reflected or scattered back to space by clouds and other atmospheric particles. About 19% of the energy available is absorbed by clouds, gases (like ozone), and particles in the atmosphere. Of the remaining 55% of the solar energy passing through the Earth's atmosphere. 4% is reflected from the surface back to space. On average, about 51% of the Sun's radiation reaches the surface. This energy is then used in a number of processes, including the heating of the ground surface; the melting of ice and snow and the evaporation of water; and plant photosynthesis. (3) The heating of the ground by sunlight causes the Earth's surface to become a radiator of energy in the long wave band (sometimes called in the radiation). This emission of energy is generally directed to space. However, only a small portion of this energy actually makes it back to space. The majorly of the outgoing infrared radiation is absorbed by the greenhouse gases. (4) Absorption of long wave radiation by the atmosphere Causes additional heat energy to be added to the Earth's atmospheric system. The now warmer atmospheric greenhouse gas molecules begin radiating long wave energy in all directions. Over 90% of this emission of long wave energy is directed back to the Earth's surface where it once again is absorbed by the surface. The heating of the ground by the long wave radiation causes the ground surface to once again radiate, repeating the cycle described above, again and again, until no more long wave is available for absorption. (5) The amount of heat energy added to the atmosphere by the greenhouse effect is controlled by the concentration of greenhouse in the Earth's atmosphere. All of the major greenhouse gases have increased in concentration since the beginning of the industrial Revolution. As a result of these higher concentrations. Scientists predict that the greenhouse effect will be enhanced and the Earth's climate will become warmer. Predicting the amount of warming is accomplished by computer modeling Computer models suggest that a doubling of the concentration of the main greenhouse as carbon dioxide, may raise the average global temperature between 1 and 3º Celsius. However, the numeric equations of computer models do not accurately simulate the effects of a number of possible negative feedbacks. For example, many of the models cannot property Simulate late the negative effects that increased cloudier. These extra clouds would then reflect a greater proportion of the sun's energy back to space reducing the amount of molar radiation absorbed by the atmosphere and the Earth's surface. With less solar energy being absorbed at the surface, the effects of an enhanced greenhouse effect may be counteracted. (6) A number of gases are involved in the human caused enhancement of the greenhouse effect. These gases include carbon dioxide (CO2): methane (CH4): nitrous oxide: (N2O): chlorofluorocarbons (CFC): and troposphere ozone (O3). Of these gases the single most important gas in carbon dioxide, which accounts for about 55% of the change in the intensity of the Earth's greenhouse effect. The contributions of the other gases are 25% for chlorofluorocarbons, 15% for methane, and 5% for nitrous oxide. Ozone's contribution to the enhancement of greenhouse effect is still yet to be quantified. (7) Average concentrations of atmospheric carbon dioxide in the year 2005 were about 380 parts per million. Prior to 1700, levels of carbon dioxide were about 280 parts per million. This increase in carbon dioxide in the atmosphere is primarily due to the activities of humans. Beginning in 1700, societal change brought about by the industrial Revolution. Increased the amount of carbon dioxide entering the atmosphere. The major Sources of this gas include fossil fuel combustion for industry, Transportation, space heating, electricity generation, and cooking, and vegetation changes in natural prairie, woodland, and forested ecosystems. Emissions from fossil fuel combustion account for about 65% of the extra carbon dioxide now found in our atmosphere. The remaining 35% is derived from deforestation and the conversion of prairie, woodland and forested ecosystems primarily into agricultural systems. (8) Artificially created chlorofluorocarbons (CFCs) are the strongest greenhouse gas per molecule. However, low concentrations in the atmosphere reduce their overall importance in the enhancement of the greenhouse effect. Current measurements in the atmosphere indicate that the concentration of these chemicals may soon begin declining because of reduced emissions. Reports of the development of ozone holes over the North and South Boles and a general decline in global Stratosphere ozone level over the last two decades has caused many nations to cut back on their production and use of the chemicals. In 1987, the signing of the Montreal Protocol agreement by forty-six nations established an immediate timetable for the global reduction of CFC production and use. (9) Since 1750, methane concentrations in the atmosphere have increased by more than 150%. The primary sources for the additional methane added to the atmosphere (in order of importance) are rice cultivation, domestic grazing animals, termites, landfills, coal mining, and oil, and gas extraction. Anaerobic conditions associated with rice paddy flooding results in the formation of methane gas. However, an accurate estimate of how much methane is being produced from rice paddies has been difficult to obtain. More than 60% of all rice paddies are found in India and China were scientific data concerning emission rates are unavailable. Nevertheless, scientists believe that the contribution of rice paddies is large because this form of crop production has more than doubled since 1950.