What does advection fog mean? How is advection fog classified?

Lead: The easiest way to judge clouds and fog is to see if they touch the ground. Clouds are not grounded, and fog is grounded. There are many kinds of fog. Some friends don't know advection fog, so they want to know what advection fog means. How is advection fog classified? Let's have a look.

What does advection fog mean?

Advection fog is a fog formed when the warm and humid air flows horizontally to the cooler underlying surface and the lower part cools. It often happens in winter and spring, especially in the northern coastal areas, which can "wrap" the buildings in the city and make people on the ground feel like they are in a fairyland. Advection fog cannot do without the horizontal flow of air. As long as there is a persistent wind, the fog will last for a long time. If the wind stops and the source of warm and humid air is interrupted, the fog will soon dissipate.

Advection fog classification

Advection cooling fog

In advection fog, warm air is cooled by the sea surface and water vapor condenses. This kind of advection fog is relatively strong, and advection fog has a large area, long duration and low visibility. Spring is more common in the Kuril Islands in the western North Pacific and the waters near Newfoundland in the western North Atlantic.

Advection evaporation fog

Advection fog is formed by seawater evaporation and water vapor saturation in the air. Cold air flows to the warm ocean. Due to the cold and warm air in the lower level, stratification is unstable. Therefore, although advection fog has a large area, the advection fog layer is not thick, and advection fog is not thick. When cold air from the polar regions reaches the nearby warm sea surface or waters near huge icebergs, advection will occur to evaporate the advection fog.

Typical Multi-advection Fog City in China

Due to the unique urban terrain, Qingdao has foggy weather all the year round, especially advection fog and radiation fog. For example, on March 26, 20 14, dense fog enveloped Qingdao, overlooking the tall buildings, and only the top of the tall buildings was exposed in the clouds, which was a dreamy color. However, while creating beautiful scenery, fog is also harmful to some extent. When it appears, toxic and harmful substances and air pollutants in the air may have a series of physical and chemical reactions, thus producing new toxic and harmful substances.

2065438+0165438 On the morning of 29 October 2008/KLOC-0, a rare advection fog landscape appeared on both sides of Hongshui River, the county seat of Dahua Yao Autonomous County, Hechi City, Guangxi Province, overlooking Dahua County from the air. Against the backdrop of the morning glow, the whole county is looming in the foggy sea, just like a fairyland.

On the evening of March 27th, 2020, advection fog appeared in Xiamen, Fujian Province. The whole island is shrouded in mist, and urban buildings are looming. Affected by the foggy weather, the visibility of the main channel of Xiamen Port decreased, and the visibility of some waters was less than 200 meters. Xiamen Maritime Safety Administration issued foggy traffic control that night, suspending ships from entering and leaving the port.

On June 2, 2022, advection fog landscape appeared in Qingdao West Coast New District.

The relationship between fog and weather

Fog is ever-changing and complicated, but it is nothing more than radiation fog and advection fog. Although there are various phenomena, the essence is the same: water vapor condenses when it meets cold. Sometimes fog indicates sunny days, sometimes fog indicates rainy days, and it looks chaotic. However, as long as the characteristics of radiation fog and advection fog are mastered, observed in many aspects and carefully analyzed, the laws of fog, sunny and rainy weather can be accurately grasped, and the weather can be predicted. This is very useful for agriculture, transportation, aerospace and navigation.

Fog is closely related to future weather changes. The working people in China have known this truth since ancient times, and it is reflected in many folk proverbs. For example, "Huangmei is foggy, rocking the boat doesn't ask for directions." This means that the fog at the turn of spring and summer is a harbinger of rain, so people also have the saying of "summer fog and rain". Another example is: "I can't see anyone in the fog, so I dare to wash my clothes." This means that winter fog is sunny, and so is autumn fog.

To accurately understand the sky through fog, we must also look at the duration of fog. Radiation fog is caused by cold weather and water vapor condensation, so it disappears when the temperature rises during the day, and the weather is fine; On the other hand, "fog is rain." If the fog doesn't disperse during the day, it may rain the next day, so the folk proverb says, "The fog doesn't reach noon, and the rain will ring after noon."