What is the cause of fog from the perspective of high school geography?

Fog genesis: In the absence of wind or static wind, the warm and moist air flow meets the cold underlying surface.

Water vapor in the air condenses into a fog. From the above causes, we can analyze that there are three conditions:

1. It is windless or still wind; 2. There is warm and humid airflow; 3. There is a cold underlying surface.

Of course, this also applies to fog on land. Then, "when cold and warm currents meet, sea fog often forms, that is, conditions 2 and 3 are metIn addition, globally, where sea fog occurs more is also where there are more fishing grounds.

There are also two types of fishery causes, including the place where the cold and warm currents meet (Hokkaido Fishing Ground).

Newfoundland Fisheries), and Upwelling (Peru.

Fishery) cold and warm currents meet many sea fog has been said before, why is there also a lot of sea fog in the upwelling place?

It is mostly found in tropical desert climates.

The seaside has a tropical desert climate and a Mediterranean climate.

In summer, the climate is characterized by high temperature and little rain, but the temperate zone of day and night is large, and the land temperature is low before and after sunrise (condition 3) is under the control of the subtropical high (condition 3).

The ocean temperature is higher than that of the land, forming relatively warm and humid air currents (condition 2) Therefore, the seaside with tropical desert climate and Mediterranean climate is prone to sea fog such as the West Coast of the United States.

below), the Peruvian coast, the southwest coast of Africa (where recent mock questions have come up frequently) and the northwest coast.

Fog is mainly a phenomenon produced by a large amount of water vapor when the temperature decreases. 1.As the altitude rises, the temperature decreases, and it happens that the water vapor rises from the bottom to form fog.

2.In the morning, the direct angle of the sun is low, and there is a certain amount of heat that causes a large amount of water vapor to form. In areas that happen to be a little higher, the temperature is low and fog is formed.

The conditions for the formation of sea fog in high school geography are as follows:

One situation: in the middle and low latitudes, due to the strong solar radiation, the evaporation of seawater is more vigorous, and the weather is warm and humid. When a cold snap flows, it causes the temperature near the ocean to drop, and as the temperature drops, the water vapor in the air condenses, forming sea fog.

Two scenarios: in the middle and high latitudes, the solar radiation is weaker and the temperature is lower.

The concept of sea fog:

Sea fog is a phenomenon of water vapour condensation (hua) in the lower atmosphere above the ocean, which reduces horizontal visibility to less than 1 kilometre due to the accumulation of water droplets or ice crystals (or both), and the thickness of the fog is usually around 200 400 metres. When sea fog forms at sea, it drifts with the wind and expands downstream of the wind.

In coastal areas, sea fog can make landfall deep into land, sometimes up to tens of kilometers, and after landfall, the sea fog still retains the characteristics of sea fog, but under the new environmental influence, it quickly denatures and dissipates, or becomes a low cloud. Offshore, the sea fog that makes landfall is constantly dissipating, but it is constantly replenished from the sea, so the sea fog sometimes lasts for several days in coastal areas.

Specific causes of the formation of sea fog:

Fog and clouds are water vapor condensates made up of small droplets or ice crystals floating in the air, except that fog is formed in the near-surface layer of the atmosphere, while clouds are formed in the higher layers of the atmosphere. Since fog is a condensate of water vapor, its cause should be found in the conditions that cause the condensation of water vapour.

The conditions for the formation of sea fog in high school geography are as follows:

1. Sea surface temperature.

A large number of observations confirm that advection fog mostly occurs over cold sea surface waters. In particular, in the waters where the surface temperature of the sea water decreases rapidly along the direction of the air flow, that is, on the cold water surface of the cold and warm current intersection area or in the area where the horizontal temperature gradient is large, the warm and moist air flow moving through it is more likely to denature and cool and condense the water vapor, and fog is more frequent in these waters.

2. Sea temperature difference.

In addition to the condition that the surface water temperature is lower than a certain limit value, the false judgment of advection fog also depends on the cooperation of sea surface water temperature and meteorological conditions, including the cooperation between water temperature and air temperature.

3. Airflow wind field.

The long-term existence of warm and humid airflow is very important for the formation and development of sea fog, which can continuously replenish a large amount of water vapor and heat necessary for fog to the fog area. Therefore, when fog is generated, southerly or easterly airflow generally prevails. In our country, the direction of the wind that favors the formation of fog varies depending on the sea area.

Generally speaking, the East China Sea has the most fog when the wind is southerly, and the fog is most common when the South China Sea is windy.

Sea fog distribution:

Although there are many types of sea fog in various sea areas around the world, the advection cooling fog is the first to be promoted with large scope and serious impact, and the two banded fog areas centered on Newfoundland Island in the mid-high latitude Atlantic Ocean and the Kuril Islands in the North Pacific Ocean are the most significant, and the banded fog area centered on the Prince Edward Islands in the South Indian Ocean is also prominent.

The second is fog in the upper reaches of the low-latitude trade wind belt on the east coast of the ocean, such as off the coast of California and Peru on the east coast of the Pacific Ocean, and the waters south of the Canary Islands on the east coast of the Atlantic Ocean and off the coast of Namibia. Sea fog in these areas is mostly prevalent in spring and summer, especially in summer. It is characterized by a thick fog that lasts for a long time, and severe fog can last for 1 to 2 months.

Advection evaporative fog is mostly found in the subpolar regions or the outer edge waters of icebergs and drift ice in the cold season, and the fog layer is thin and resembles cooking smoke. However, when it alternates with advection cooling fog in mid and high latitudes in spring and autumn, it often forms a large area of dense fog.