MEMPHIS, Tenn. (WMC) - Now that the days are getting shorter and the air is much cooler, you may notice more foggy mornings.
Autumn is known for more fog and the reason is because the nights are getting longer and the longer nights allow the temperatures to fall to the dew point. Night time hours will continue to get longer through December 21, which is the Winter Solstice.
As the air cools, it can’t hold as much moisture, so the water vapor condenses into tiny moisture droplets that remain suspended in the air which we know as fog. When we get into late fall, humidity levels tend to drop and wind speeds increase, which are not ideal for fog formation.
The month of October can be really foggy across the Mid-South, especially during the morning hours. Our close proximity to the Mississippi River can make steam fog more common as well. In October humidity levels can sometimes still be quite high, which would allow for more fog formation. In the Mid-South, fog can occur at any time of year, but it is far more likely in the fall.
Fog will dissipate as the sun heats the ground near the fog’s edge, mixing drier air into the fog and allowing it to evaporate. Typically ground fog will dissipate at its edges first, where its is more shallow, followed by the thicker center of the fog.