Why is it so dry in winter?

When the temperature is high in summer, water is easy to evaporate into steam, so the more steam there is in the air, the wetter the air is. In winter, the temperature is low and there is little water vapor in the air, so it is dry.

In geography, we call the degree of dryness and wetness of air "humidity".

Of course, the reason why the air is dry in winter is not only the geographical reason why temperature affects water evaporation, but also:

1. For most parts of China, there is less precipitation in winter, so less water can evaporate into the atmosphere and the air is dry.

2. The amount of water vapor contained in a certain amount of air is limited, which is called saturation, that is, the relative humidity is 100%. In winter, the air with low temperature can hold less water vapor, which means that even if enough water evaporates, the air with low temperature will appear dry.

3. There is also a physiological reason: after we inhale air in winter, the air is heated to body temperature, and the relative humidity will become very low (the same absolute humidity is different at different temperatures), so we will feel dry. The air we exhale is basically saturated steam at body temperature, so we consume a lot of water when we breathe. The air near the skin will also be heated, so the water in the skin will easily evaporate. All these will make us feel very dry in winter.