In the spring in the south, whenever the weather returns to the south, the walls, blackboards and floors of the classroom are very wet, and even "water" will come out. ...

"Returning to Nantian" is a phenomenon of weather resurgence, which generally occurs in February and March in Guangdong in spring. The main reason is that the warm and humid airflow acts quickly after the cold air, which leads to the rapid increase of temperature and air humidity. Some cold objects are easy to produce water droplets after encountering warm and humid airflow, which is also called "spitting wet". The dense fog is the most distinctive appearance of "returning to the south sky".