When it is windy, we can fly a kite. But where does the wind come from? What makes the wind move all the time? Scientists explain that it is the sun. The sun makes the air move, and makes it blow. When the sun shines on the earth, it makes the earth hot. Then the earth, like a big oven, makes the air hot. When the air becomes hotter, it also becomes lighter and rises. This gives the cool air a chance to come in and take the place of the hot air. The hot light air goes up higher and higher until it becomes cool. Then it comes down again, and the earth makes it hot again, and it goes upwards again. When the air moves, we have wind.
刮风时，我们可以放风筝。但风是从哪里来的呢？是什么让风不停地移动？科学家解释说，这是因为太阳。太阳让空气流动，形成风。当太阳照在地球上时，地球变热。然后，地球就像一个大烤箱，使空气变热。当空气变得更热时，它也变得更轻并上升。这让冷空气有机会进来并取代热空气。轻的热空气升得越来越高，直到变冷。然后空气再下降，地球又再次把它加热，它再次上升。当空气流动时，就有了风。