- 最后登录
- 2022-11-23
- 在线时间
- 1571 小时
- 寄托币
- 4677
- 声望
- 348
- 注册时间
- 2015-3-26
- 阅读权限
- 100
- 帖子
- 1019
- 精华
- 1
- 积分
- 3485
- UID
- 3605802
  
- 声望
- 348
- 寄托币
- 4677
- 注册时间
- 2015-3-26
- 精华
- 1
- 帖子
- 1019
|
发表于 2015-4-14 15:54:59
|显示全部楼层
本帖最后由 无敌浩克One 于 2015-4-14 15:58 编辑
2015.4.14 comprehension note!
The molecules of carbon dioxide in the Earth’s atmosphere affect the heat balance of the Earth by acting as a one-way screen. Although these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concentrated, to pass through, they absorb some of the longer-wavelength, infrared emissions radiated from the Earth’s surface, radiation that would otherwise be transmitted back into space. For the Earth to maintain a constant average temperature, such emissions from the planet must balance incoming solar radiation. If there were no carbon dioxide in the atmosphere, heat would escape from the Earth much more easily. The surface temperature would be so much lower that the oceans might be a solid mass of ice.
Today, however, the potential problem is too much carbon dioxide. The burning of fossil fuels and the clearing of forests have increased atmospheric carbon dioxide by about 15 percent in the last hundred years, and we continue to add carbon dioxide to the atmosphere. Could the increase in carbon dioxide cause a global rise in average temperature, and could such a rise have serious consequences for human society? Mathematical models that allow us to calculate the rise in temperature as a function of the increase indicate that the answer is probably yes.
Under present conditions a temperature of-18℃ can be observed at an altitude of 5 to 6 kilometers above the Earth. Below this altitude (called the radiating level), the temperature increases by about 6℃ per kilometer approaching the Earth’s surface, where the average temperature is about 15℃. An increase in the amount of carbon dioxide means that there are more molecules of carbon dioxide to absorb infrared radiation. As the capacity of the atmosphere to absorb infrared radiation increases, the radiating level and the temperature of the surface must rise.
One mathematical model predicts that doubling the atmospheric carbon dioxide would raise the global mean surface temperature by 2.5℃. This model assumes that the atmosphere’s relative humidity remains constant and the temperature decreases with altitude at a rate of 6.5℃ per kilometer. The assumption of constant relative humidity is important, because water vapor in the atmosphere is another efficient absorber of radiation at infrared wavelengths. Because warm air can hold more moisture than cool air, the relative humidity will be constant only if the amount of water vapor in the atmosphere increases as the temperature rises. Therefore, more infrared radiation would be absorbed and reradiated back to the Earth’s surface. The resultant warming at the surface could be expected to melt snow and ice, reducing the Earth’s reflectivity. More solar radiation would then be absorbed, leading to a further increase in temperature.
17. The primary purpose of the passage is to
(A) warn of the dangers of continued burning of fossil fuels
no obvious warn in passage
(B) discuss the significance of increasing the amount of carbon dioxide in the atmosphere
the first paragraph talked about how C02 helps to maintain the surface temperature, otherwise, the earth would be covered by ice, this is the importance of C02
actually, the description of B isn't accurate, but it is better than any other choices
(C) explain how a constant temperature is maintained on the Earth’s surface
narrow the scope, this is only the first part of the passage, the other three part talked about the temperature increase
(D) describe the ways in which various atmospheric and climatic conditions contribute to the Earth’s weather
no various atmospheric and climatic conditions, only C02 and moisture
(E) demonstrate the usefulness of mathematical models in predicting long-range climatic change
narrow the scope, mathematical models only used to predict the condition of earth
18. According to the passage, the greatest part of the solar energy that reaches the Earth is
(A) concentrated in the infrared spectrum
infrared spectrum has been absorbed by C02, thus can't reach
(B) concentrated at visible wavelengths
relative sentence: Although these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concentrated, to pass through
(C) absorbed by carbon dioxide molecules
reaches earth, so isn't absorbed by C02
(D) absorbed by atmospheric water vapor
similar to C
(E) reflected back to space by snow and ice
if reflected, it can't reach
19. According to the passage, atmospheric carbon dioxide performs all of the following functions EXCEPT:
in the first paragraph
(A) absorbing radiation at visible wavelengths
CO2 allows visible wavelengths to pass through
(B) absorbing infrared radiation
(C) absorbing outgoing radiation from the Earth
(D) helping to retain heat near the Earth’s surface
(E) helping to maintain a constant average temperature on the Earth’s surface
20. Which of the following best describes the author’s attitude toward the increasing amount of carbon dioxide in the atmosphere and its consequences?
(A) Incredulous
wrong, no doubt, just stated evidence
(B) Completely detached
wrong, completely is excessive
(C) Interested but skeptical
wrong, no skeptical
(D) Angry yet resigned
wrong, no angry
(E) Objective yet concerned
first, the author just stated several statements but no opinion, so the attitude could be objective, objective here means the opposite of subjective.
21. It can be concluded from information contained in the passage that the average temperature at an altitude of 1 kilometer above the Earth is about
surface 15, increases by about 6 per km
15-6=9
(A) 15℃
(B) 9℃
(C) 2.5℃
(D) -12℃
(E) -18℃
22. It can be inferred from the passage that the construction of the mathematical model mentioned in the passage involved the formulation of which of the following?
relative sentence: This model assumes that the atmosphere’s relative humidity remains constant and the temperature decreases with altitude at a rate of 6.5℃ per kilometer.
so the assumption is not the amount of C02, or human activities, but a physical condition(moisture)
(A) An assumption that the amount of carbon dioxide added to the atmosphere would in reality steadily increase
(B) An assumption that human activities are the only agencies by which carbon dioxide is added to the atmosphere
(C) Assumptions about the social and political consequences of any curtailment of the use of fossil fuels
(D) Assumptions about the physical conditions that are likely to prevail during the period for which the model was made
(E) Assumptions about the differential behavior of carbon dioxide molecules at the various levels of temperature calculated in the model
23. According to the passage, which of the following is true of the last hundred years?
(A) Fossil fuels were burned for the first time.
not mentioned
(B) Greater amounts of land were cleared than at any time before.
no comparison with earlier time
(C) The average temperature at the Earth’s surface has become 2℃ cooler.
no quantitative statistics of temperature
(D) The amount of carbon dioxide in the atmosphere has increased measurably.
relative sentence: The burning of fossil fuels and the clearing of forests have increased atmospheric carbon dioxide by about 15 percent in the last hundred years
(E) The amount of farmland worldwide has doubled.
not mentioned farmland worldwide |
|