CNN News:冰雨和雨夾雪的形成

Of course, weather plays a part too in Thanksgiving travel. And except for the Pacific Northwest, forecasters are predicting decent Thanksgiving weather for most of the U.S. It should be a welcome relief to travelers in Chicago, Illinois, where hundreds of flights were cancelled over the weekend.

當然了，在感恩節(jié)旅行中，天氣也很重要。除了太平洋西北地區(qū)，天氣預報員預測，美國大部分地區(qū)感恩節(jié)天氣良好。這對于芝加哥以及伊利諾斯州的游客來說是一件非常欣慰的事情，因為在上個周末數百個航班取消。

The season`s first big snowstorm arrived. Some parts of the northern U.S. were buried under as much as 20 inches of snow. There were problems for drivers as well, with freezing rain and sleet, making things dangerous on the roads.

原因是首場暴風雪來臨了。美國北部部分地區(qū)積雪深達20英寸。這對汽車司機而言也是難題，冰雨以及雨夾雪使行駛在路上非常的危險。

SUBTITLE: Freezing rain versus sleet.

標題：冰雨和雨夾雪

It all comes down to the temperature at different levels of the atmosphere.

冰雨和雨夾雪是因為不高度的大氣層溫度不同而形成的。

Take freezing rain, for example. You start with a snowflake high in the atmosphere. It will enter a warm layer, temperatures above freezing. That will cause the snowflake to melt and basically turn into a raindrop.

例如，冰雨，在高空中是雪花，之后雪花進入溫度在0攝氏度以上暖層。這就會引起雪花融化，雪花就會變成雨滴。

That warm layer is so thick that temperatures don`t get below freezing until just above the surface, not enough time for that raindrop to freeze again. So, it freezes on everything it makes contact with, roads, bridges, power lines, tree branches, everything.

暖層溫度不低于冰點，并且很厚，融化的雨滴沒有時間再次凍結。所以，雨滴就會凍結與所接觸的事物，道路、橋梁、電線、樹枝等等。

On the other hand, you have sleet, the only difference is that warm layer isn`t so thick and the raindrop has enough time to freeze again. That`s why a lot of times you can hear sleet. It sounds like ice hitting the surface -- roads, cars, anything it touches.

另一方面，雨夾雪是因為暖層厚度較薄，致使雨滴有足夠的時間再次凍結。這就是你經常聽到雨夾雪聲音的原因。它聽起來就像冰擊打道路、汽車等所接觸東西表面。