63 Clouds, Wind, and Storms-High

Clouds, Wind, and Storms Written by Kira Freed

《云、风和风暴》作者:基拉·弗里德

Introduction Somewhere on Earth, almost every type of weather is happening right now. Some places have light, puffy clouds. Heavy rain or snow is falling in other places. Did you ever wonder what causes all these types of weather? Our planet is surrounded by a layer of air called the atmosphere. The atmosphere is made of masses of air that are constantly moving and mixing. Warm air masses mix with cold air masses. Dry air masses mix with wet air masses. The mixing of air masses causes wind, clouds, precipitation, and storms.

在地球上的某个地方，现在几乎所有类型的天气都在发生。 有些地方有轻盈的浮云。 其他地方正在下大雨或大雪。 你有没有想过是什么原因导致了这些类型的天气? 我们的星球被一层叫做大气层的空气包围着。 大气是由不断移动和混合的气团组成的。 暖气团与冷气团混合。 干气团与湿气团混合。 气团的混合导致风、云、降水和风暴。

Weather happens near Earth's surface. The Sun's energy warms Earth's surface, which warms the air above it. But not all surfaces are heated equally. The parts of Earth closer to the equator get more heat than polar regions. Darker surfaces absorb more energy than lighter surfaces. Also, Earth's tilt makes parts of Earth get more sunlight than other parts during different seasons. When air that has received more heat from Earth's surface mixes with air that has received less energy, the result is weather. Weather is determined by the amount of wind, clouds, and precipitation.

天气发生在地球表面附近。 太阳的能量使地球表面变暖，从而使地球表面的空气变暖。 但并不是所有的表面都受到同样的加热。 地球上靠近赤道的部分比极地吸收更多的热量。 深色表面比浅色表面吸收更多能量。 此外，地球的倾斜使得地球的某些部分在不同的季节比其他部分得到更多的阳光。 当从地球表面接收到更多热量的空气与接收到较少能量的空气混合时，就形成了天气。 天气是由风量、云量和降水量决定的。

Wind Wind is simply air on the move. We can't see it, but we can feel it. And we can see its effects on plants, flags, wind chimes, and other things. As air near Earth's surface gets warmed by its heat, the air gets lighter. The colder air, which is heavier, pushes down on it, squeezing it upward. As the warm air rises, it cools. As the cold air gets closer to the ground, it warms. Air is always moving, warming, and cooling, which makes wind.

风就是移动的空气。 我们看不见它，但我们能感觉到它。 我们可以看到它对植物、旗帜、风铃和其他东西的影响。 当地球表面附近的空气被热量加热时，空气变轻了。 较冷的空气较重，向下挤压，向上挤压。 当暖空气上升时，它就会冷却。 当冷空气接近地面时，它就变暖了。 空气一直在流动，变暖，变冷，这就形成了风。

Think about the city of Chicago, which is on Lake Michigan. When the Sun is shining, the air over land heats up more than the air over water. As warm air over the city rises, cooler air over the lake moves toward the land to replace the rising warm air. The movement of air creates a breeze from the lake to the land. This is called a sea breeze. Why is wind strong sometimes and just a light breeze at other times. Wind is stronger when the difference in temperature between the warm air mass and the cool air mass is great. When this happens, the cold air "chases" the warm air faster.

想想密歇根湖边的芝加哥市。 当太阳照耀时，陆地上的空气比水面上的空气热得多。 当城市上空的暖空气上升时，湖面上的冷空气就会向陆地移动，取代上升的暖空气。 空气的运动产生了从湖泊吹向陆地的微风。 这就是海风。 为什么有时风很大，有时只是微风。 当暖气团和冷气团之间的温差很大时，风就会更强。 当这种情况发生时，冷空气会更快地“追赶”暖空气。

Changes in weather are created when air masses of different temperatures meet each other. The line where a warm air mass and a cold air mass meet is called a front. Changes in weather tend to happen along a front. Have you ever noticed the lines on a weather map? Those lines show the location of fronts. Measuring the Wind We measure the wind with an instrument called an anemometer. People measure the wind for many reasons. Information about wind speeds helps scientists predict the weather. Airplane pilots cannot take off or land if the wind is blowing too hard. Ship captains require safe wind speeds to enter harbors. Machines called wind turbines convert fast- moving wind into electricity. In some locations, the wind is too calm to use wind turbines.

当不同温度的气团相遇时，天气就会发生变化。 暖气团和冷气团相遇的线叫做锋面。 天气的变化往往沿着锋面发生。 你注意过天气图上的线条吗? 这些线表示前线的位置。 测量风我们用一种叫做风速计的仪器来测量风。 人们测量风有很多原因。 风速信息有助于科学家预测天气。 如果风力太大，飞行员就无法起飞或降落。 船长需要安全的风速才能进港。 被称为风力涡轮机的机器将快速移动的风转化为电能。 在一些地方，风太平静，不能使用风力涡轮机。