We know the weather on the radio and TV every day.
If we read correctly the signs around us, we can tell what the more important changes in the weather will be. This way of telling what the weather will be like in the following days is called weather forecasting(预报).
For many centuries, people have studied the weather and tried to make weather forecasting. Many people feel hurt in their bones with the coming of wet weather. Their joints ache. Some birds fly high if fine weather is coming, but they fly near the ground if rainy or stormy weather is on the way. If you see a rainbow during rainy weather, this is a sign that the weather will become clear and fine. If the stars twinkle clearly at night, then fine weather will continue. If a fog appears in the morning just above a river, then the day will be warm. If the sunset is mostly red in colour, then the following day will be fine.
Most of the above sayings have been made by people who have used their eyes and brains to make weather forecasting. Now, the idea of weather forecasting is developing incredibly(难以置信地) quickly.