Breakdown: What’s fog and why does it form?

Breakdown: What's fog and why does it form?

MEMPHIS, TN (WMC) -You may have noticed lately more fog, across the Mid-South. But have you ever wondered what it is and how it forms?

Fog is a type of cloud that’s close to or touches the ground. Fog is made up of many very tiny water droplets or ice crystals.

When the air close to the ground, is cooled, water vapor condenses, into tiny liquid water droplets, suspended in the air. This can occur because of added moisture or falling ambient air temperatures. The difference between air temperature and dew point is less than 4.5 degrees Fahrenheit when fog can form.

This can occur because of added moisture or falling air temperatures. The difference between air temperature and dew point is less than 4.5 degrees Fahrenheit when fog forms.

There are five different types of fog.

Radiation fog often happens in the fall and winter. It forms under clear skies and calm conditions, when air cools and becomes stable. When the cooling reaches the dewpoint fog forms.

Valley fog is another type of fog where cold dense air will move and settle over valleys as it condenses, it forms fog.

Advection fog also called sea fog, usually forms over seas and is caused by warm, moist air moving over cooler waters.

Upslope fog is a type of fog that is formed when air flows over a rising surface like mountains and is cooled to its dew point.

Evaporation fog is formed when precipitation falls into drier air, the liquid droplets evaporate into water vapor. The water vapor then cools to its dewpoint, it condenses and fog forms.

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