What kind of weather is a cold wave?

Cold wave is a kind of disastrous weather in winter, and people are accustomed to call it cold wave. The so-called cold wave is a weather process in which cold air from the north invades our country southward on a large scale, causing large-scale rapid cooling and northerly winds. Cold waves generally occur in late autumn, winter, and early spring. my country's meteorological department stipulates that if the temperature drop caused by the intrusion of cold air reaches more than 10℃ within a day, and the minimum temperature is below 5℃, then this cold air outbreak process is called a cold wave process. It can be seen that not every cold air moving south is called a cold wave.