In wet weather, white gas will come out when the refrigerator door is opened. Why?

When you open the refrigerator in summer, there will be "white gas" in the refrigerator, which is formed by the liquefaction of water vapor in the air when it is cold. In fact, it is a droplet in the form of gas.

There is a certain amount of water vapor in the air. Due to the sudden drop of temperature, it reaches saturation or saturation state, so it can't accommodate so much water vapor as originally contained. At this point, the excess water vapor will form tiny water droplets, forming clouds of floating fog-like water droplets, which will turn into white water vapor after being irradiated by light, that is, "white gas" as seen.

Note: this "white gas" is not "water vapor", because water vapor is a colorless and transparent gas, which is invisible.