Listen to English every day!
천천히 듣기




Winter weather/ has returned/ to northern areas of the world. In much of the United States, winter/ means the return of snow. Snow/ is a subject/ of great interest/ to weather experts. Experts/ 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.

Snow/ is a form/ of frozen water. It contains many groups/ of tiny ice particles/ called snow crystals. These crystals/ grow from water particles/ in cold clouds. They usually grow/ around a piece of dust. 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 -- platelike and columnar. Platelike crystals/ are flat. They form/ when the air temperature/ is about fifteen degrees/ below zero Celsius. 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 sleet.

Groups of frozen water droplets/ are called/ snow pellets. Under some conditions, these particles/ may grow larger/ and form solid pieces of ice, or hail.

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

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

Much of the water/ we use/ comes from snow. Melting snow/ provides water/ for rivers, electric power centers/ and agricultural crops. In the western United States, mountain snow/ provides up to seventy-five percent/ of all surface water supplies.

Snowfall/ helps to protect plants/ and some wild animals/ from cold, 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 greatly reduced.

Snow/ also is known/ to influence the movement/ of sound waves. When there is fresh snow/ on the ground, the surface of the snow/ takes in, or absorbs, sound waves. However, snow/ can become hard and flat/ as it becomes 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 travel farther.

Generally, the color of snow and ice/ appears 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 travel path/ through the snow or ice. In simple terms, 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, all the 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 extreme northern and southern areas/ of the world/ 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 coastal mountains/ of western Canada, and the Sierra Nevada and Rocky Mountains/ in the United States. In warmer climates, snow/ is known/ to fall in areas over four thousand nine hundred meters/ above sea level.

Each year, the continental United States/ has an average/ of one hundred snowstorms. An average storm/ produces snow/ for two to five days. Almost every part of the country/ 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 nineteen ninety-eight/ and nineteen ninety-nine. Two thousand eight hundred ninety-five centimeters of snow/ fell at the Mount Baker Ski area/ in the northwestern state of Washington.

People/ in many other areas/ have little or no snowfall. In nineteen thirty-six, a physicist/ from Japan/ produced the first man-made snow/ in a laboratory. During the nineteen-forties, several 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, special machines/ are used/ to produce limited amounts of snow/ for winter holiday ski areas.

Snow/ 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 extreme physical activity.

Several years ago, a major storm/ caused serious problems/ in the eastern United States. It struck the Southeast/ in January, ninety ninety-six, before moving up the East Coast. The storm/ was blamed/ for more than one hundred deaths. It forced nine states/ to declare emergency measures.

Virginia and West Virginia/ were hit/ hardest. In some areas there, snowfall amounts/ were more than one meter high. Several states/ limited driving/ to emergency vehicles. Most major airports/ were closed/ for at least a day or two.

A week later, two other storms/ brought additional snow/ to the East Coast. In the New York City area, the added weight/ of the snow/ forced the tops of some buildings/ to break down. Many travelers/ were forced to walk long distances/ through deep snow/ to get to train stations.

People/ may not be able to avoid living/ in areas/ where it snows often. However, they can avoid/ becoming victims/ of winter snowstorms. People should stay/ in their homes/ until the storm/ has passed. While removing large amounts of snow, they should stop/ and rest often.

Difficult physical activity/ during snow removal/ can cause a heart attack. It is always a good idea/ to keep a lot of necessary 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/ to prevent the possibility/ of carbon monoxide gas poisoning.

People/ 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/ to look at, but it can also be dangerous.
목록