61 Clouds, Wind, and Storms-Low

Clouds. Wind. and Storms Written by Kira Freed

云。风。以及基拉·弗里德的《风暴》

Introduction Somewhere on Earth almost every kind of weather is happening right now. Do you wonder what causes weather? Earth is surrounded by a layer of air. This layer is called the atmosphere. The air may be warm or cold. It may be dry or wet. Different kinds of air mix with each other all the time. This causes wind, clouds, precipitation, and storms.

在地球上的某个地方，现在几乎各种天气都在发生。 你想知道是什么导致了天气吗? 地球被一层空气层包围着。 这一层叫做大气。 空气可能是温暖的，也可能是寒冷的。 它可能是干的或湿的。不同种类的空气一直相互混合。 这就导致了风、云、降水和风暴。

The Sun's energy hits Earth and turns to heat. The warm ground heats the air above it. Warm and cool air mix to make weather. Some parts of Earth get more energy than others. The North and South Poles get less heat than Earth's middle. Dark parts get more heat than light parts. Parts of Earth also get more sunlight than others during different seasons.

太阳的能量撞击地球并转化为热量。 温暖的地面加热了地面上的空气。 冷暖空气混合形成了天气。 地球上的一些地方比其他地方获得更多的能量。 北极和南极得到的热量比地球中部少。 暗的部分比亮的部分得到更多的热量。 在不同的季节里，地球上的一些地方也比其他地方得到更多的阳光。

Wind Wind is air that moves. We can't see it, but we can feel it. We can see how it moves plants, flags, and other things. Air moves because the ground warms air next to it. Warm air is lighter than cold air, so it rises. The cold air above sinks to the ground because it is heavier. As that cold air gets warmer, it starts to rise. Then other cold air takes its place. All this heating and cooling of air makes wind.

风是流动的空气。 我们看不见它，但我们能感觉到它。 我们可以看到它如何移动植物、旗帜和其他东西。 空气流动是因为地面加热了旁边的空气。 暖空气比冷空气轻，所以上升。 上面的冷空气下沉到地面，因为它更重。 当冷空气变暖时，它开始上升。 然后其他冷空气取而代之。 所有这些空气的加热和冷却形成了风。

The city of Chicago is a good example of a place where mixing air of different temperatures makes wind. Chicago is on a lake. When the Sun shines, the air over land gets warmer than the air over water. Warm air over the city rises. Cool air over the lake moves toward the land and replaces the warm air that rose. This causes wind to blow from the lake to the land. The larger the temperature difference between the hot and cold air, the stronger the wind.

芝加哥就是一个很好的例子，不同温度的空气混合在一起就会产生风。 芝加哥在一个湖上。当太阳照耀时，陆地上的空气比水面上的空气温暖。 城市上空的暖空气上升。 湖面上的冷空气向陆地移动，取代上升的暖空气。 这导致风从湖吹到陆地。 冷热空气的温差越大，风就越强。

Changes in weather happen when air of different temperatures meets. Did you ever see the lines on a TV weather map? Those lines show where warm and cold air meet. The lines are called fronts. MEASURING THE WIND We measure the wind with an anemometer. Why do people measure the wind? Here are some reasons. Knowing wind speed helps scientists predict the weather. Airplane pilots cannot take off or land if the wind is blowing too hard. Ship captains need safe wind speeds to enter harbors. Machines called wind turbines turn strong wind into electricity. In some places, the wind is too calm to use wind turbines.

当不同温度的空气相遇时，天气就会发生变化。 你见过电视天气图上的线吗? 这些线表示冷暖空气相遇的地方。 这些线被称为前线。 测量风我们用风速计测量风。 人们为什么要测量风? 这里有一些原因。了解风速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强风转化为电能。 在一些地方，风太平静，不能使用风力涡轮机。