B
Particles from car exhausts generate more persistent clouds but less rain, new research suggests. Furthermore, putting more of these particles into the atmosphere reduces the low-level winds, which could reduce the amount of wind power available in very polluted regions. The dry but populated regions may therefore suffer a triple blow as a result of vehicle pollution：less water, less hydropower and less wind energy.
Scientists studied the effects of aerosol（浮质）pollution from cars and industry. They correlated satellite data on wind speeds and the amount of aerosol particles in the atmosphere above the South Coast Basin in California and above China. Results showed that higher concentrations of aerosols were closely associated with slower ground winds. Scientists then used computer models to support the idea that there was a cause and effect relationship behind this correlation.
Particles floating in the atmosphere block energy from the Sun, preventing it from warming the surface of the Earth. Cooler surface temperatures during the day means the low—level and slow moving air does not rise up and mix with the faster winds at higher altitudes. Slower winds also induce less evaporation from oceans, rivers and lakes. And finally, once clouds have formed, they store less moisture in the form of rain. This is because raindrops form around small particles— dust, for instance, or pollution. With more particles in the atmosphere, it takes longer for enough water to condense（凝结）onto a particle to form a raindrop. And if the cloud of fine droplets（小滴）moves to a drier area before its would-be rain can rail, the moisture evaporates once more and the cloud disappears.
Scientists note their new work does not contradict previous findings that suggest global warming might lead to more tropical storms, because there is far less particulate（微粒的）pollution over the oceans.
60. The first paragraph mainly talks about .
A. the results of vehicle pollution
B. an introduction to particles from car exhausts
C. less wind energy in polluted regions
D. less water caused by vehicle pollution
61. From this passage we can learn that .
A. scientists supported their idea by using material models
B. the new study is contrary to the previous findings
C. if there are more particles in the atmosphere, there will be more raindrops
D. there is a cause and effect relationship between wind speeds and particle pollution
62. The underlined word “induce” in Paragraph 3 most probably mean _ .
A. reduce B. persuade C. cause D. produce
63. What’s the best title for the passage?
A. Pollution and Global Warming B. Car, Wind and Rain
C. Industry Pollution D. How Rain Forms
