What's the meaning of "going back to the South"? Is the weather in the South beginning to appear recently? Then why does the weather in the south come into being? Let's learn about it! We must do a good job in dampproof work when we go back to the south.
What is going back to the south?
Returning to the south for short is the name given to a weather phenomenon by Guangxi, Guangdong, Fujian and Hainan in South China. It usually refers to the phenomenon that the temperature begins to warm and the humidity begins to pick up every spring.
South China is a typical marine subtropical monsoon climate. Therefore, from March to April every year, the warm and humid air from the South China Sea meets the cold air from the north to the south of China, forming a static front, which makes the weather in South China cloudy and sunny, very humid, with light rain or heavy fog.
The return to the south usually occurs in February and March of spring, which is a phenomenon of weather return.
The time period of 'back to the South' in Hainan is from January to March, and February is relatively more. It is common in Haikou, Wenchang and other northern areas of Hainan Province. Sanya, Baoting and other places in the southern area rarely see "back to Nantian" due to their unique geographical location.
When "back to the South" appears, the air humidity is close to saturation, and the walls and even the ground will "emit water". There are wet scenes everywhere. It seems that the air can wring out water. Because the south area is close to the sea, the air is humid, so it is more serious. And dense fog is the most characteristic appearance of "going back to the South". According to statistics, when the phenomenon of returning to the south is serious, the visibility can be reduced to 50m.
Why does it appear back to Nantian?
In fact, the phenomenon of returning to the south is similar to the principle of sea fog. The warm and humid ocean air flows from the warmer sea surface to the cooler sea surface, and the water vapor in the air condenses into fog drops when it is cold, and then forms fog when it accumulates in the air. If the sea surface temperature difference of air flow is large, the chance of fog formation is also large.
Similarly, affected by the cold winter weather, the walls and floors are cold inside and outside. If the warm and humid air flows through the walls and floors at this time, the water in the air will condense into water drops when it is cold, and it will be attached to the walls and floors, as if the water is seeping from the walls and floors.
Many people don't understand, so in summer, how can walls and floors not come out of water?
The reason is that even if there is moist ocean air flow in summer, the inside and outside of the walls and floors are not cold enough, so there will be no water on the walls and floors.
Before returning to Nantian, there were signs:
First of all, there is a continuous cold process, at least three days to make the indoor temperature drop to the same level as the outdoor temperature, that is, the so-called "cold through". At this time, there is a sudden change in the weather, the warm and humid air flow in the south is strengthened, and the outdoor temperature rises rapidly. At this time, although the indoor object temperature also rises, it is far behind the speed of the outdoor temperature rise, and the indoor and outdoor temperature difference is widened, resulting in the indoor object temperature less than the 'dew point' of the air, which leads to the phenomenon of returning to the south.
"Go back to Nantian" and close the doors and windows in time, especially in the morning and evening, especially the doors and windows facing south. In addition, don't open the south window when there is sunshine at noon. At noon, the outdoor temperature is high, and the indoor and outdoor temperature difference is large. At this time, ventilation will sometimes cause more serious condensation of water vapor on the indoor ground and wall. You can choose to open the doors and windows properly when there is sunshine and the relative humidity is small to absorb heat and improve the indoor air.