What is the physical phenomenon of breathing in winter?

Liquefaction. The gas exhaled by people contains water vapor, which is gaseous at high temperature (36.5 degrees Celsius) just after exhalation. In winter, when the temperature is low, the exhaled water vapor will condense into small water droplets with high concentration, so you will see white gas. This is a liquefaction phenomenon. The popsicle taken out of the refrigerator and the white gas ejected after the water is boiled are all formed by the liquefaction of water vapor. In winter, because water vapor comes out of the human body with heat, when you breathe, the water vapor coming out of your mouth suddenly meets the cold outside, liquefies into tiny water droplets, changes from gas to liquid, and becomes tiny water droplets suspended in the air.

Winter is one of the four seasons. Traditionally, it started in beginning of winter, 24 solar terms. In winter, life is closed and everything enters a state of recuperation. In winter, that is, "everything will get something", after beginning of winter, everything began to be hidden. Li Si's division of four seasons reflects many characteristics such as climate and phenology. At present, four seasons are often divided according to the temperature change, and the method of "weather average temperature" proposed by modern scholar Zhang Baokun is adopted. According to the four seasons divided by the weather average temperature method, the average daily temperature is equal to or lower than 10 degrees Celsius for five consecutive days, which is regarded as entering winter.