回南天是在中国南方地区在春季常见的一种天气现象。回南天指的是高温高湿的天气。通常，这种天气对当地居民会产生很大的影响。本期视频讲解了回南天的形成原因，并且再次提到了准静止锋的概念。

HuiNanTian is a common weather phenomenon in southern China in spring. HuiNanTian refers to high temperature and wet weather.Usually, this kind of weather has a great impact on the local residents.This video explains the formation of nantian and again introduces the concept of a quasi-stationary front.