Why is it so dry in autumn and winter?

In autumn, the weather gets cold. In order to reduce the heat emitted by the body to the outside world, the skin blood vessels contract, the pores are closed, and the activities of sweat glands and sebaceous glands are weakened, resulting in a decrease in sebum secretion, and the skin will become dry.

Winter is cold and long. Winter lasts for five months, and if the average temperature is below 0℃, it lasts for three months (1February-February). In the winter of 65438+ 10, the average temperature in the plain is below -4℃, in the mountainous area it is below -8℃, and the extreme minimum temperature in the plain is -27.4℃.

Winter precipitation accounts for 2% of the annual precipitation, and there is often no record of precipitation (snow) for more than one month. Although it is cold and dry in winter, there is a lot of sunshine, with an average of more than 6 hours of sunshine every day. Replenish water in time, eat more fruits and vegetables, keep warm and moisturize your face.

Extended data:

Skin is divided into epidermis, dermis and subcutaneous fat. The outermost layer of epidermis is stratum corneum. Because of the water absorption and barrier function of the stratum corneum itself, and the natural moisturizing factors such as amino acids, lactate and sugar contained in the stratum corneum, the stratum corneum maintains a certain water content and keeps the skin moist.

The appearance of skin is related to the moisture content of stratum corneum. Normal stratum corneum usually contains 10%-30% moisture to maintain skin softness and elasticity. However, with the increase of age, the water content of stratum corneum will gradually decrease. When the water content of stratum corneum is lower than 10%, the skin will be dry, tight, rough and desquamated.