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  • 短期气候变化

     

    What are short term  climate  changes?
    ::什么是短期气候变化?

    El Niño  and  La Niña  bring about dramatic changes in climate for a  year  or two. In some locations, one brings  rain  and the other brings  drought . In California, for example, El Niño years are full of  snow  and rain. La Niña years tend toward drought. These variations can bring tremendous changes to living creatures. Humans are also affected; for example,  erosion  from  storms  may be very high some years.
    ::厄尔尼诺和拉尼娜现象在一两年的时间里给气候带来了巨大的变化。在有些地方,一个带来降雨,另一个带来干旱。例如在加利福尼亚州,厄尔尼诺现象的年月充斥着雪雨。拉尼娜现象的年月趋向于干旱。这些变化会给生物带来巨大的变化。人类也受到影响;例如,风暴的侵蚀可能很多年。

    Short-Term Climate Change
    ::短期气候变化

    You’ve probably heard of El Niño and La Niña. These terms refer to certain short-term changes in climate. The changes are natural and occur in cycles, lasting from days to years. El Niño and La Niña are not the only short-term climate changes. Others include the Pacific decadal oscillation and the North Atlantic oscillation. El Niño and La Niña are the most noticeable and discussed.
    ::你可能听说过厄尔尼诺和拉尼娜现象。 这些术语指的是某些短期气候变化。 这些变化是自然的,周期性地发生。 厄尔尼诺和拉尼娜并不是唯一的短期气候变化。 其它的包括太平洋十月摇动和北大西洋振荡。 厄尔尼诺和拉尼娜是最引人注目和讨论过的。

    To understand El Niño and La Niña, you first need to know what happens in normal years ( Figure   ).
    ::要了解厄尔尼诺和拉尼娜,你首先需要知道正常年份会发生什么(图)。

    Ocean currents and upwelling during a normal climatic year in the Pacific.
     
    This diagram represents the Pacific Ocean in a normal year. North and South America are the brown shapes on the right.

    El Niño
    ::厄尔尼诺

    During an  El Niño , the western Pacific Ocean is warmer than usual. This causes the trade  winds  to change direction. The winds blow from west to east instead of east to west ( Figure   ). The change in the trade winds also causes the  jet streams  to be north of their normal  . The warm  water  travels east across the  equator , too. Warm water piles up along the western coast of South America. This prevents  upwelling . Why do you think this is true?
    ::在厄尔尼诺现象期间,西太平洋比往常更温暖,这导致贸易风改变方向。风从西向东吹到东,而不是从东向西吹(图 ) 。 贸易风的变化也导致喷气流以北, 热水也穿过赤道以东。 温水在南美洲西海岸堆积, 防止上升。 为什么你认为这是真的?

    These changes in water  , winds, and currents affect climates worldwide. The changes usually last a year or two. Some places get more rain than normal. Other places get less. In many locations, the   is more severe.
    ::这些水、风和海流的变化影响着全世界的气候。这些变化通常持续一年或两年。有些地方的降雨量比正常的多。另一些地方的降雨量更少。在许多地方,情况更为严重。

    Ocean currents and wind patterns during El Niño affecting South America's coast.
     
    How do you think El Niño affects climate on the western coast of South America?

    This ABC News video explores the relationship of El Niño to  . El Niño is named as the cause of strange weather across the United States in the winter of 2007.
    ::厄尔尼诺被命名为2007年冬季美国各地奇特天气的原因。

     

     

    La Niña
    ::拉尼娜

    La Niña  ( Figure   ) generally follows El Niño. It occurs when the Pacific Ocean is cooler than normal. The trade winds are like they are in a normal year. They blow from east to west. But in a La Niña, the winds are stronger than usual. More cool water builds up in the western Pacific. These changes can also affect climates worldwide.
    ::拉尼娜(Figure)一般跟随厄尔尼诺,当太平洋比正常更冷时就会发生。贸易风就像正常年一样,从东向西吹。但是在拉尼娜,风比往常强。西太平洋积聚的凉水更多。这些变化也会影响全世界的气候。

    Atmospheric and oceanic conditions during La Niña events.
     
    How do you think La Niña affects climate on the western coast of South America?

    Some scientists think that global warming is affecting the cycle of El Niño and La Niña. These short-term changes seem to be cycling faster now than in the past. They are also more extreme.
    ::一些科学家认为全球变暖正在影响厄尔尼诺和拉尼娜的循环。 这些短期变化似乎比过去更快。 它们也更加极端。

    Further Reading
    ::继续阅读

    Long-Term  Climate  Change
    ::长期气候变化

    Summary
    ::摘要

    • El Niño and La Niña are two examples of short-term climate changes lasting one to a few years.
      ::厄尔尼诺和拉尼娜是一至几年来短期气候变化的两个实例。
    • In an El Niño, the trade winds reverse direction, as do the equatorial surface currents. This causes warm water to pool off of South America and stop upwelling.
      ::在厄尔尼诺现象中,贸易风和赤道地表水流都向相反方向倾斜,这导致暖水从南美洲涌出,停止上升。
    • La Niña occurs when the Pacific Ocean is cooler than normal. Trade winds blow from east to west, but are stronger than in a normal year.
      ::拉尼娜现象发生时太平洋比正常冷却,贸易风从东向西吹,但比正常年份强。

    Review
    ::回顾

    1. In which direction does wind blow during an El Niño event?
      ::厄尔尼诺现象发生时风吹向哪个方向?
    1. In which direction does current go during an El Niño event?
      ::厄尔尼诺现象发生时,当前走向何方?
    1. How is a La Niña different from an El Niño?
      ::拉尼娜与厄尔尼诺有何不同?
    1. During an El Niño, what happens to life off the coast of South America and why?
      ::在厄尔尼诺期间,南美沿岸的生活会怎样,为什么?