Patchy dense fog settled across eastern Kentucky Sunday morning. Some locations reported visibility near zero at times (visibility map from Sunday at 8am below). More patchy fog, although not as dense, is expected Monday morning as well.
So how do we know this will happen? There are several ingredients meteorologists use to forecast fog. Fog develops when the air becomes saturated, which means the air is holding as much water vapor as it can. When this happens, the invisible water vapor condenses into tiny water droplets that make up the fog, which is really just a cloud over the ground. Ask an elementary school student about this. They will be excited to explain the condensation part of the water cycle!
Now to some of the things we look for when forecasting fog:
Fog dissipates once the sun rises and starts warming the ground, which in turn warms the air from the ground, up. That is why the fog typically dissipates or “lifts” from the ground into stratus clouds above. This image is from our UPike weather camera over downtown Pikeville Sunday morning, which shows this nicely. Two hours later, temperatures warmed up enough from the dew point to dissipate the fog and there was full sunshine into the afternoon.
Hopefully you were able to learn a thing or two about one of many weather features we forecast every day. Enjoy your week!
-Meteorologist Brandon Orr (Find me on Facebook!)