CHICOPEE, Mass. (WWLP) – Dense fog across western Massachusetts Thursday morning.
There are many types of fog, but this fog is called radiation fog, which clear skies and calm winds is needed. On cloudy nights, when Earth’s surface gives off heat, the clouds will re-radiate that heat back toward the ground and that prevents temperatures from cooling down more significantly.
With clear skies overnight, the Earth’s surface gives off more heat, and that cools down the air to its dew point. Radiation fog is also more likely after rain because it moistens up the soil and increases dew points. There was plenty of rain Wednesday.
Air cools to its dew point, becoming saturated, forming fog. But, there’s one more important ingredient: light wind. If winds are too high that causes mixing of the air, preventing fog from forming.