How is the fog formed?

Fog is formed by the cooling of steam.

The formation of fog requires three conditions: first, cooling, when there is enough water vapor in the air, the breeze is just right, the atmosphere is stable, the temperature near the ground drops, and the water vapor cools to form fog; Followed by humidification. The formation of fog requires a relative humidity of 100%. When the humidity does not reach the standard, it is necessary to continuously increase the water vapor content until the humidity reaches the standard. Finally, there must be condensation nuclei. Under the conditions of humidity and cooling, condensation nuclei need to be formed before fog can appear.

One is cooling, which is the main condition for fog formation. When the air is full of moisture and the humidity reaches 100%, then cooling is the key. Because if there is no cooled water vapor, it is difficult for water vapor to condense, so it is difficult for fog to appear.

Second, humidity, humidity is a necessary condition for fog formation, and it can also be regarded as a raw material for fog formation. If there is not enough humidity and enough water vapor, then fog cannot be formed. Under normal circumstances, the humidity of this water vapor should reach saturation, otherwise even if the temperature drops, it is difficult to form fog due to insufficient water vapor.

Third, condensation nuclei, water vapor conditions, and cooling conditions depend on whether they can condense at this time. Only when water droplets or ice crystals are formed can fog be formed. Of course, the most important thing here is to have cooling and enough water vapor. After cooling, condensation nuclei generally appear.