What is the phenomenon of extremely cold weather?

Extreme cold weather refers to the weather below -40℃.

According to the "cold degree scale" formulated by meteorological specialty, the temperature ranges from below -40℃ to 9.9℃, and it is divided into eight grades from low to high. One of them is extremely cold.

In recent years, in Europe and Asia, severe snowstorms have caused the lowest temperature in many areas in a hundred years. Moreover, heavy snow caused the interruption of aviation, railway and highway transportation, and many towns lost contact with the outside world, power supply was interrupted, and natural gas supply was tight. The lowest temperature in parts of Inner Mongolia and Heilongjiang also fell below -40℃, which is related to extremely cold weather.