It's too cold. Why is it so cold?

It's so cold that I don't even want to have a runny nose. My hands and feet are numb with cold. When the weather is too cold, people will feel cold and uncomfortable. This is because low temperature will cause blood vessels to contract, reduce the flow of blood, and then slow down the metabolism of the body, and all parts of the body will feel cold. In addition, when the temperature is low, the skin and mucous membrane on the human surface will also be stimulated by cold, resulting in tingling and discomfort. Together, these factors will lead to the start of the body's self-protection mechanism, resulting in cold, sneezing and other reactions, as well as numbness of hands and feet, runny nose and other symptoms.