Drought and Its Causes Vocabulary and Expressions deficiency humanitaria

游客2023-12-29  17

问题 Drought and Its Causes
Vocabulary and Expressions
deficiency       humanitarian       erosion      paradoxically
atmospheric     prevalence         adversely     sunshade
migration       exacerbate [br] What makes drought regularly occurring along the Midwest American and in Australia?
Drought and Its Causes
   Drought is an extended period when a region receives a deficiency in its water supply, whether atmospheric, surface or ground water. A drought can last for months or years, or may be declared after as few as 15 days. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region. Although droughts can persist for several years, even a short, intense drought can cause significant damage and harm to the local economy. Prolonged droughts have caused mass migrations and humanitarian crises.
   Generally, rainfall is related to the amount of water vapor carried by regional atmosphere, combined with the upward forcing of the air mass containing that water vapor. If these combined factors do not support precipitation volumes sufficient to reach the surface, the result is a drought. This can be triggered by high level of reflected sunlight and above average prevalence of high pressure systems, winds carrying continental, rather than oceanic air masses, and ridges of high pressure areas from behaviors which prevent or restrict the developing of thunderstorm activity or rainfall over one certain region. Oceanic and atmospheric weather cycles make drought a regular recurring feature of the Americas along the Midwest and Australia.
   Human activity can directly trigger exacerbating factors such as over farming, excessive irrigation, deforestation, and erosion adversely impact the ability of the land to capture and hold water. While these tend to be relatively isolated in their scope, activities resulting in global climate change are expected to trigger droughts with a substantial impact on agriculture throughout the world, and especially in developing nations. Overall, global warming will result in increased world rainfall. Along with drought in some areas, flooding and erosion will increase in others. Paradoxically, some proposed solutions to global warming that focus on more active techniques, solar radiation management through the use of a space sunshade for one, may also carry with them increased chances of drought.

选项 A、High level of reflected sunlight.
B、Oceanic and atmospheric weather cycles.
C、Above average prevalence of high pressure systems.
D、Shortage of thunderstorm activity.

答案 B

解析 根据原文“Oceanic and atmospheric weather cycles make drought a regular recurring feature of the Americas along the Midwest and Australia”判断,美国中西部和澳大利亚干旱频繁发生的原因是海洋性天气和大气环流,故本题应该选B。
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