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VOA慢速英语2013 SCIENCE IN THE NEWS - Let It Snow, Let it Snow, Let It Snow!

时间:2013-01-31 08:54:33

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SCIENCE IN THE NEWS - Let It Snow, Let it Snow, Let It Snow!

From VOA Learning English, this is SCIENCE IN THE NEWS, in Special English. I’m Bob Doughty1.

And I’m Faith Lapidus. Today, we will tell you about a winter storm that brought heavy snowfall to the Middle East. And we will tell you everything you ever wanted to know about snow.

Snowfall is common in many areas during the winter. But snow recently fell in some places where it is rarely seen. The eastern Mediterranean2 received what has been called its worst winter storm in 20 years in early January. Weather experts say the storm produced as much snow and rainfall as the average precipitation totals for all winter long.

The storm affected3 life in many cities, from Gaza to Istanbul. It also worsened the suffering of hundreds of thousands of Syrian refugees4 and the one million other Syrians displaced5 from their homes by almost two years of conflict.

As much as 15 centimeters of snow fell in cities like Jerusalem, Ramallah, Amman and Damascus. As much as 30 centimeters of snow covered rural areas of Jordan and northern Israel. Officials there closed public transportation, schools, and government offices because of the snow. Many businesses did not open because their workers could not get to work.

But the news was not all bad. Some people enjoyed the snowfall. Israeli President Shimon Peres went outside and placed a hat on a snowman.

“It is so rare, so beautiful, so unifying6. Whatever happens in Jerusalem is a blessing7. This time it’s a blessing in white.”

Snow is a subject of great interest to weather experts. They sometimes have difficulty estimating where, when or how much snow will fall. One reason is that heavy amounts of snow fall in surprisingly small areas. Another reason is that a small change in temperature can mean the difference between snow and rain.

Just what is snow, anyway? Snow is a form of frozen9 water. It contains groups of ice particles called snow crystals. These crystals grow from water droplets10 in cold clouds. They usually grow around dust particles.

All snow crystals have six sides, but they grow in different shapes. The shape depends mainly on the temperature and water levels in the air.

Snow crystals grow in one of two designs: plate-like and columnar. Plate-like crystals are flat. They form when the air temperature is about 15 degrees below zero Celsius11. Columnar snow crystals look like sticks of ice. They form when the temperature is about five degrees below zero.

The shape of a snow crystal may change from one form to another as the crystal passes through levels of air with different temperatures. When melting snow-crystals or raindrops fall through very cold air, they freeze to form small particles of ice, called sleet12. Groups of frozen water-droplets are called snow pellets. Under some conditions, these particles may grow larger and form solid pieces of ice, or hail13. Hail can be dangerous to people, animals and property.

When snow crystals stick together, they produce snowflakes. Snowflakes come in different sizes. As many as 100 crystals may join to form a snowflake larger than two and one-half centimeters. Under some conditions, snowflakes can form that are five centimeters across. Usually, this requires near-freezing temperatures, light winds and changing conditions in Earth’s atmosphere. 

Snow contains much less water than rain. About two and one-half centimeters of rain has as much water as 15 centimeters of wet snow. About 76 centimeters of dry snow equals the water in two and one-half centimeters of rain.

Much of the water the world uses comes from snow. Melting snow provides water for rivers, power stations and crops. Mountain snow provides up to 75 percent of all surface water supplies in the western United States.

Snowfall helps to protect plants and some wild animals from winter weather. Fresh snow is made largely of air trapped among the snow crystals. Because the air has trouble moving, the movement of heat is limited.

Snow also influences the movement of sound waves. When there is fresh snow on the ground, the surface of the snow absorbs, or takes in, sound waves. However, snow can become hard and flat as it grows older or if there have been strong winds. Then, the snow’s surface will help to send back sound waves. Under these conditions, sounds may seem clearer and may travel farther.

Generally, snow and ice appear white. This is because the light we see from the sun is white. Most natural materials take in some sunlight. This gives them their color. However, when light travels from air to snow, some light is sent back, or reflected. Snow crystals have many surfaces to reflect sunlight. Yet the snow does take in a little sunlight. It is this light that gives snow its white appearance. 

Sometimes, snow or ice may appear to be blue. The blue light is the product of a long path through the snow or ice. Think of snow or ice as a filter. A filter is designed to reject some substances, while permitting others to pass through. In the case of snow, light makes it through if the snow is only a centimeter thick. If it is a meter or more thick, however, blue light often can be seen.

Snow falls in the Earth’s extreme North and South throughout the year. However, the heaviest snowfalls have been reported in the mountains of other areas during winter. These areas include the Alps in Italy and Switzerland, the coastal14 mountains of western Canada, and the Sierra Nevada and Rocky Mountains in the United States. Snow is even known to fall near the Equator15, but only on the highest mountains.

Each year, the continental16 United States has an average of 105 snowstorms. An average storm produces snow for two to five days. 

Almost every part of the United States has received snowfall at one time or another. Even parts of southern Florida have reported a few snowflakes.

The national record for snowfall in a single season was set in the winter of 1998 to 1999. Two thousand eight hundred ninety-five centimeters of snow fell at the Mount8 Baker17 Ski area in the northwestern state of Washington. 

People in many areas have little or no natural snowfall, but they still want to see snow. So scientists have come up with a solution. In 1936, a physicist18 from Japan produced the first man-made snow in a laboratory. Then, during the 1940s, American scientists developed methods for making snow in other areas. Clouds with extremely cool water are mixed with man-made ice crystals, such as silver iodide and metaldehyde crystals. Sometimes, dry ice particles or liquid propane are used. Today, machines are used to produce limited amounts of snow for ski areas when not enough natural snow has fallen. 

Snow may be beautiful, but it can be deadly. It is responsible for the deaths of hundreds of people in the United States every year. Many people die in traffic accidents on roads that are covered with snow or ice. Others die from being out in the cold, or from heart attacks caused by too much physical activity. 

You may not be able to avoid living in areas where it snows often. However, you can avoid becoming a victim of a snowstorm. Most people are told to stay in their homes until the storm has passed. When removing large amounts of snow, they should stop and rest often. Difficult physical activity during snow removal can cause a heart attack, especially among older adults. 

It is always a good idea to keep a lot of supplies in the home, even before winter begins. These supplies include food, medicine, clean water and extra power supplies.

Some drivers have become trapped in their vehicles during a snowstorm. If this happens, people should remain in or near their car unless they see some kind of help. They should get out and clear space around the vehicle’s exhaust pipe to prevent the possibility of carbon monoxide poisoning.

Drivers should tie a bright-colored object to the top of their car to increase the chance of rescue. Inside the car, they should open a window a little for fresh air and turn on the engine for ten or fifteen minutes every hour for heat.

People living in areas where winter storms are likely should carry emergency supplies in their vehicle. These include food, emergency medical supplies and extra clothing to stay warm and dry. People in these areas should always be prepared for winter emergencies. Snow can be beautiful, but it can also be dangerous.


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1 doughty Jk5zg     
adj.勇猛的,坚强的
参考例句:
  • Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质:脾气倔强,性格刚强。
  • The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。
2 Mediterranean ezuzT     
adj.地中海的;地中海沿岸的
参考例句:
  • The houses are Mediterranean in character.这些房子都属地中海风格。
  • Gibraltar is the key to the Mediterranean.直布罗陀是地中海的要冲。
3 affected TzUzg0     
adj.不自然的,假装的
参考例句:
  • She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
  • His manners are affected.他的态度不自然。
4 refugees ddb3b28098e40c0f584eafcd38f1fbd4     
n.避难者,难民( refugee的名词复数 )
参考例句:
  • The UN has begun making airdrops of food to refugees. 联合国已开始向难民空投食物。
  • They claimed they were political refugees and not economic migrants. 他们宣称自己是政治难民,不是经济移民。
5 displaced 80a237e34fd2de4119d9d640b29506b6     
移动( displace的过去式和过去分词 ); 替换; 移走; 撤职
参考例句:
  • Gradually factory workers have been displaced by machines. 工厂的工人已逐渐被机器取代。
  • He was displaced by another young man. 他已被另一个年轻人顶替。
6 unifying 18f99ec3e0286dcc4f6f318a4d8aa539     
使联合( unify的现在分词 ); 使相同; 使一致; 统一
参考例句:
  • In addition, there were certain religious bonds of a unifying kind. 此外,他们还有某种具有一种统一性质的宗教上的结合。
  • There is a unifying theme, and that is the theme of information flow within biological systems. 我们可以用一个总的命题,把生物学系统内的信息流来作为这一研究主题。
7 blessing UxDztJ     
n.祈神赐福;祷告;祝福,祝愿
参考例句:
  • The blessing was said in Hebrew.祷告用了希伯来语。
  • A double blessing has descended upon the house.双喜临门。
8 mount 6Fixv     
n.山峰,乘用马,框,衬纸;vi.增长,骑上(马);vt.提升,爬上,装备
参考例句:
  • Their debts continued to mount up.他们的债务不断增加。
  • She is the first woman who steps on the top of Mount Jolmo Lungma.她是第一个登上珠穆朗玛峰的女人。
9 frozen 2sVz6q     
adj.冻结的,冰冻的
参考例句:
  • He was frozen to death on a snowing night.在一个风雪的晚上,他被冻死了。
  • The weather is cold and the ground is frozen.天寒地冻。
10 droplets 3c55b5988da2d40be7a87f6b810732d2     
n.小滴( droplet的名词复数 )
参考例句:
  • Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
  • In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反,从人嘴里呼出的烟则包含相当大的水滴,所以呈白色。 来自辞典例句
11 Celsius AXRzl     
adj.摄氏温度计的,摄氏的
参考例句:
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
12 sleet wxlw6     
n.雨雪;v.下雨雪,下冰雹
参考例句:
  • There was a great deal of sleet last night.昨夜雨夹雪下得真大。
  • When winter comes,we get sleet and frost.冬天来到时我们这儿会有雨夹雪和霜冻。
13 hail LQ4z0     
n.雹,一阵;vi.下雹;vt.高呼,为...喝彩
参考例句:
  • Hail fell with such violence that it broke windows.冰雹猛落,把玻璃窗也砸破了。
  • The people lined the streets to hail the returning heroes.人们夹道欢迎凯旋的英雄们。
14 coastal WWiyh     
adj.海岸的,沿海的,沿岸的
参考例句:
  • The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
  • This country will fortify the coastal areas.该国将加强沿海地区的防御。
15 equator piJzt     
n.赤道,(平分球形物体的面的)圆
参考例句:
  • Singapore is near the equator.新加坡位于赤道附近。
  • The United States is north of the equator.美国位于赤道以北。
16 continental Zazyk     
adj.大陆的,大陆性的,欧洲大陆的
参考例句:
  • A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
  • The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。
17 baker wyTz62     
n.面包师
参考例句:
  • The baker bakes his bread in the bakery.面包师在面包房内烤面包。
  • The baker frosted the cake with a mixture of sugar and whites of eggs.面包师在蛋糕上撒了一层白糖和蛋清的混合料。
18 physicist oNqx4     
n.物理学家,研究物理学的人
参考例句:
  • He is a physicist of the first rank.他是一流的物理学家。
  • The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

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