36.High School English Listening

For those of us lucky enough to always have enough food andwater, it may be hard to imagine living through a drought.
A drought occurs when for a variety of reasons, usually includinga lack of rainfall and warm temperatures.
Soil moisture severely dwindles.
Why and how do these meteorological event soccur?
As air swirls around the earth, it rises and sinks over different areas of the globe.
When air rises itcools and loses moisture.
When air sinks, it grows warmer and absorbs moisture, drying out theland.
Sinking air helps to form deserts, such as the Sahara Desert in Africa.
Warm, sinking air can hamper cloud formation, which results in less rain and lower overall humidity.
When these conditions occur in an area that normally receives enough rain to allow plants to grow and keep water sources replenished, a drought can ensue.
The Dust Bowl that affected the prairie regions of the United States was one infamous drought.
An equally severe drought occurred in the United States in the summer of 1988.
Rainfall over the mid-west,Northern Plains, and the Rockies was fifty to eighty-five percent below normal.
Sometimes over-farming and soil erosion contribute to drought, but there are also natural disasters that can occur even when soil is carefully preserved.
And when a drought hits, there'slittle that can be done to end it.
Water and soil conservation can help, but until the rains comeagain there's not much science can do.译文：
对于我们这些幸运的人来说，总是有足够的食物和水，可能很难想象在干旱中生活。
干旱发生时，由于各种原因，通常包括缺乏降雨和温暖的温度。
土壤水分严重减少。
为什么以及如何发生这些气象事件？
当空气围绕地球旋转时，它在全球不同地区上升和下沉。
当空气上升时，它变冷并失去水分。
当空气下沉时，它变得更暖和，吸收水分，使土地变干。
下沉的空气有助于形成沙漠，如非洲的撒哈拉沙漠。
温暖、下沉的空气会阻碍云的形成，从而导致雨量减少和整体湿度降低。
当这些情况发生在一个通常有足够雨水让植物生长并保持水源补充的地区时，干旱就会随之而来。
影响美国大草原地区的沙尘暴就是一场臭名昭著的干旱。
1988年夏天，美国发生了一场同样严重的旱灾。
中西部、北部平原和落基山脉的降雨量比正常水平低50%至85%。
有时过度耕作和土壤侵蚀会导致干旱，但即使土壤被精心保护，也会有自然灾害发生。
而当干旱来临时，几乎没有什么可以做来结束它。
水和土壤保护可以提供帮助，但在雨水再次到来之前，科学能做的不多。
重点词汇：
enough to 足够…去做 ; 足以 ; 足够……可以
drying out 焦枯
Sinking air 【体】下降气流
such as 例如 ; 像 ; 象…这样 ; 诸如…之类
air can Air Canada (formerly Trans-Canada Air Lines) 加拿大航空公司
cloud formation 云之形成