冬季北方的寒冷气流向南侵袭,如同潮水一样滚滚而来,常常造成大范围的急剧降温。我国气象部门规定:在24小时内气温急剧下降10摄氏度以上,最低气温在5摄氏度以下时称为“寒潮”。寒潮每年一般自10月开始,11～12月最强,次年4月结束。寒潮过境时,寒冷气流移动速度为每小时20～50公里,寒潮前锋部分冷锋 In winter, the cold airstream in the north strikes south and flows in the same direction as the tide, often resulting in a wide range of rapid cooling. China’s meteorological department provides: a sharp drop in temperature within 10 hours of 10 degrees Celsius, the lowest temperature below 5 degrees Celsius called “cold wave.” Cold wave each year generally from October, the strongest in 11 ~ December, the end of April the following year. Cold wave transit, the cold air flow rate of 20 to 50 kilometers per hour, cold front part of the cold front