The spectacle of "sea of ??fog" appears over the city of Changsha. Why does this phenomenon occur?

On the morning of January 29, the spectacle of "Sea of ??Fog" appeared over the city of Changsha. The misty clouds and mist reflected the golden sunrise, and the city seemed to be covered with a thin veil, making it particularly beautiful. ?It’s too beautiful to be true? It’s like a dream. Many citizens who live in high-rise buildings have posted the beautiful scenery in the fog on their WeChat Moments. Mr. Liu, a citizen who lives in Yanghu, said that when he got up and opened the window, there was heavy fog outside, and he thought he was in a fairyland.

? Go to work with the navigation on? Can’t see 50 meters with your hand? When you go to work, you don’t know if you are lost. This morning’s heavy fog has caused trouble for many citizens when traveling. Some citizens complained: ?I can’t find you wherever you are in the mist and rain on so many towers. ?

Although the sea of ??fog is beautiful, many citizens are worried about whether it is the haze. Provincial meteorological experts said that there is no need to worry too much, the foggy sea scenery is actually radiation fog. ?After long periods of rain, it is easy to produce radiation fog. ?Meteorological experts said that Hunan has had sunshine during the past two days, and the temperature has been low in the morning, resulting in radiation fog. But the citizens living in Hedong expressed their dissatisfaction. Under the same sunshine, why is there no such thing as Hedong? Meteorological experts explained that there are generally three conditions for fog to occur: First, high humidity at low altitudes. Second, the atmospheric stratification is stable, the wind speed is small, and the air does not produce convection. Low-altitude water vapor does not spread to the surroundings. Third, it needs to be carried out under cooling. Along rivers or lakes, the temperature changes are lower than on land, and the air humidity is high. Water encounters cold air and condenses into small water droplets, which is more likely to form fog. The Yanghu Wetland Park area has more water vapor and high air humidity, forming clouds and fog. scene?. The reporter learned from the Municipal Meteorological Observatory that seas of fog appear in winter, mostly advection fog or radiation fog. Advection fog is a fog formed when warm, moist air moves to cooler land or water, and the lower part is cooled. It usually occurs in winter and spring. The period of occurrence is not fixed, but it lasts longer and has a larger range; radiation fog It is mainly caused by ground radiation cooling at night, which saturates the water vapor in the air. Therefore, fog often occurs in winter when the night is the longest and the temperature is the lowest, or in the colder winter half of the year.