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  • General

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  • 暴风雪

    Snow-covered street with cars driving during a heavy snowfall.
     

    Where are the snowiest cities in the world?
    ::世界上最雪的城市在哪里?

    Four of the world’s top ten snowiest cities are in northern Japan, where cold   from Asia pick up moisture as they pass over the Sea of Japan.  The city of Sapporo receives an average of 479 cm (189 in) per  year , and holds a world-renowned  Snow  Festival every winter.  Most of the other snowiest cities are in North America and lie east of the Great  Lakes  in New York, Pennsylvania, and Quebec. This area receives  lake-effect snow . If you plan to visit these cities in winter, strap on your snow shoes!
    ::世界上最大的十大雪天城市中,有四个位于日本北部,亚洲的寒冷在横渡日本海时吸收了水分。 札幌市平均每年收到479厘米(189厘米),每个冬天都举办世界知名的雪节。 其他最雪天城市大多位于北美,位于纽约、宾夕法尼亚和魁北克大湖以东。这个地区会遭受湖水效应雪。 如果您打算在冬天访问这些城市,请系上雪鞋!

    Winter Storms
    ::冬季风暴

    Like  , winter  storms  develop from  . But in the case of winter storms, the cyclones form at higher latitudes. In North America, cyclones often form when the  jet stream  dips south in the winter. This lets dry polar air pour south. At the same time, warm moist air from the Gulf of Mexico flows north. When the two air masses meet, the differences in   and pressure cause strong  winds  and heavy  . Blizzards and lake-effect snow storms are two types of winter storms that occur in the U.S.
    ::例如,冬季风暴从冬季暴风中发展出来。但是在冬季暴风中,气旋在高纬度地区形成。在北美,气旋往往在喷气流在冬季向南倾斜时形成。这让干燥的极地空气向南倾注。与此同时,来自墨西哥湾的温暖潮湿空气向北流动。当两个空气团相遇时,气流和压力的差异导致强风和强力。暴风和湖效应雪暴是美国发生的两种冬季风暴。

    Blizzards
    ::头晕

    A  blizzard  ( Figure   ) is a snow storm that has high winds. To be called a blizzard, a storm must have winds greater than 56 kilometers (35 miles) per hour and visibility of ¼ mile or less because of wind-blown snow.
    ::暴风雪( Figure ) 。 暴风雪( Figure ) 是一场高风雪。 暴风雨的风势必须大于每小时56公里(35英里 ) , 风雪的可见度则大于或小于1⁄4英里。

    Snow-covered landscape with trees, reduced visibility, and a pedestrian crossing sign.
     
    Blizzard in Washington, D.C. Blizzards are unusual in Washington, D.C. Do they ever occur where you live?

    Blizzards are dangerous storms. The wind may blow the snow into deep drifts. Along with the poor visibility, the snow drifts make driving risky. The wind also makes cold temperatures more dangerous. The greater the wind speed, the higher the  windchill .  Windchill  is what the temperature feels like when the wind is taken into account. It depends on air temperature and wind speed ( Figure   ). Higher windchill will cause a person to suffer frostbite and other harmful effects of cold sooner than if the wind isn't blowing.
    ::暴风雪是危险的风暴。 风可能会把雪吹到深处。 除了可见度低, 雪会漂移使驾驶风险更大。 风也会使寒冷温度更加危险。 风速越快, 风铃就越高。 风速越高。 风速越高, 风速越高。 风速越快, 风速越快。 风速越快, 风速就越快。 风速越快, 风速越快, 风速越快。 风速越快, 风速越快, 风速越快, 风速越快, 风速越快, 风速越快。

    NWS Windchill Chart showing frostbite times based on temperature and wind speed.
     
    Windchill temperatures may be very low in blizzards because of the high wind speeds. How long does it take for frostbite to occur when the air temperature is 0° F and the wind speed is 55 miles per hour?

    Lake-Effect Snow
    ::影响湖湖的雪雪

    Some places receive very heavy snowfall just about every winter. If they are near a lake, they may be getting  lake-effect snow . The image below shows how lake-effect snow occurs ( Figure   ). Winter winds pick up moisture as they pass over the relatively warm waters of a large lake. When the winds reach the cold land on the other side, the air cools. Since there was so much moisture in the air, it can drop a lot of snow. More than 254 centimeters (100 inches) of snow may fall in a single lake-effect storm!
    ::有些地方大约每个冬天都会降下非常大的雪,如果它们靠近湖泊,它们可能会遭受湖水效应的雪。下面的图像显示的是湖水效应雪是如何发生的(图 ) 。 冬季风在经过一个大湖相对温暖的水域时会得到水分。 当风到达另一边的寒冷地带时, 空气会冷却。 由于空气中存在如此多的水分, 它会降下大量的雪。 超过254厘米( 100英寸)的雪可能会在一次湖水效应风暴中降下!

    Lake-effect snow formation due to warm lake water and cold land.
     
    Lake-effect snow falls on the east side of lakes in North America. These snows are heaviest on the east sides of the Great Lakes.

    Summary
    ::摘要

    • Blizzards are often part of a mid-latitude cyclone. The jet stream brings cold air into contact with warm moist air.
      ::暴风雪往往是中纬度旋风的一部分,喷气流使冷空气与温暖潮湿空气接触。
    • The difference in pressure between the air masses brings about strong winds.
      ::空气质量的压力差异 带来了强风
    • Cold polar air absorbs moisture as it travels over the Great Lakes. The air cools when it goes back over land and then dumps snow. This creates lake-effect snow.
      ::寒冷的极地空气在穿越五大湖时吸收水分,空气在回到陆地后会冷却,然后倾倒雪。这造成了湖效应雪。

    Review
    ::回顾

    1. What is the difference between a snowstorm and a blizzard?
      ::暴风雪和暴风雪有什么区别?
    1. Under what circumstances does a blizzard form?
      ::在什么情况下暴风雪会形成?
    1. What two conditions cause the largest blizzards?
      ::哪些两个条件导致最大的暴风雪?
    1. What causes lake-effect snow?
      ::是什么导致了湖效应雪?