What weather is foggy?

Fog and weather fog are clouds on the ground, and clouds are fog in the sky. Because clouds and fog are formed by condensation of water vapor in the air after cooling, they just appear in different positions. Clouds are floating in the sky and the ground is covered with fog. In order to see the fog accurately, we must contact the weather before the fog. As the saying goes, "sunny and foggy for a long time, foggy and sunny for a long time." "Because it is sunny for a long time, there is little water in the air. Although the temperature drops at night, there is generally no fog. If there's fog, it's something else: the warm and humid air in the place invades quietly, forming advection fog, so the weather will turn rainy in the future. On the contrary, there is a lot of water in the air after the rain. Because the clouds cover the earth with a quilt, the geothermal energy is not easy to dissipate. When the temperature drops at night, the temperature difference is not large, and fog cannot be formed. If there is heavy fog, it is a typical radiation fog, because the clouds in the sky split at night, which leads to a strong cooling on the ground and the weather will clear up. To accurately understand the sky through fog, we must look at the concentration of fog. Radiation fog is formed by condensation of water vapor in surface air, so it is relatively light. You can see the blue sky through the fog; Advection fog, on the other hand, is formed by the cold of a wide range of warm and humid air, which looks quite dense. The intensity of this fog has a lot to do with the weather. It is based on this relationship that people sum up their own experience: "The fog is small and the weather is fine; The fog is thick and there is strong wind; Fog and heavy rain are fierce; The next day it was foggy and sunny. "You can tell the sky accurately by fog, and you can also tell the color of fog. Because the radiation fog is very thin, it looks like a milky white gauze; Advection fog is very thick. Above it, it is often accompanied by clouds. It looks gloomy without sunshine. " It's white and foggy, foggy and rainy ",which is the reason. 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. "This should be explained from the knowledge of meteorology. As long as the water content in the lower air is high, when the temperature drops suddenly at night, the water will condense into fog. Fog has radiation fog, that is, fog formed under relatively clear and stable conditions. As long as the sun comes out and the temperature rises, the fog will naturally disappear. In this regard, the folk saying is: "The fog is heavy in the morning, and it will be fine for a long time." "The sun is shining in the fog, and the stone is broken. ""It's foggy in the morning, even though you are drying rice. "When people see radiation fog, it is often' ten fogs and nine sunny days'. You came to these conclusions. In autumn and winter, after the cold air in the north goes south, as the weather turns fine and sunny, the moisture content in the air gradually increases, which is easy to form radiation fog, so the fog in autumn and winter can often predict the good weather tomorrow. The fog in spring and summer is different. Most of it comes from the warm and humid air flow at sea. When it hits the cold ground, the air in the lower layer becomes cold and the water vapor condenses into fog. This fog is called advection fog. It is formed when warm and humid air from the ocean invades the mainland and suddenly encounters cold. When these warm and humid air currents meet the dry and cold air currents in the mainland, it will naturally be rainy. So the fog in spring and summer indicates rainy 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. Since ancient times, the working people in our country have known this truth, and it has been reflected in many folk proverbs. For example, "Huangmei is foggy, and when the ship shakes, it 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 clothes." "This means that winter fog is sunny, and so is autumn fog. Fog is closely related to the weather, so we can know the change of the weather through fog. However, the above explanation of radiation fog and advection fog is only for the general situation. The relationship between fog and weather is not so simple, there are many complicated contents, which cannot be copied mechanically, but should be analyzed in detail. In other words, if we want to know fog accurately, we need observation, analysis and comprehensive judgment in many aspects. In order to make more contributions, everyone should know about fog.