Fog, in the context of Environmental Science (EVS), is a weather phenomenon that happens when warmer air interacts with cold air. This interaction leads to the condensation of water vapor into liquid water, forming fog.
Understanding Fog Formation
The key factor in fog formation is the relationship between air temperature and the amount of water vapor it can hold. Cold air holds less water vapor than warm air. Therefore, when warm, moist air cools, it reaches a point where it can no longer hold all the water vapor. The excess water vapor condenses into tiny water droplets, which are suspended in the air, creating fog.
Types of Fog
According to the provided reference, there are three main types of fog:
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Radiation Fog: This type forms on clear, calm nights when the ground cools rapidly through radiation, cooling the air above it.
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Advection Fog: This fog occurs when warm, moist air moves horizontally over a cold surface, such as cold water or land.
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Fog in Cooler Climates: This is a broader category referring to fog that is common in regions with generally cold temperatures, which facilitates the condensation process.
Example
Imagine warm, moist air moving over a cold lake. As the warm air passes over the cold water, it cools down. Because cold air cannot hold as much water vapor as warm air, the water vapor in the air condenses into tiny water droplets, creating fog over the lake. This is an example of advection fog.
