The reason why much of Central Missouri saw fog this morning
You may have noticed there was a lack of visibility this morning, either while driving to work or while taking a morning walk. Much of Central Missouri saw areas of dense fog during the early to mid-morning hours before it gradually dissipated in the later morning hours. Places like Columbia, Jefferson City, Sedalia, and the Lake of the Ozarks were some of the many areas where fog was observed.
One of the most common ways fog is observed in Missouri is by what is known as radiation fog. This typically happens during the warmer months on clear and calm nights with light winds. Once the sun sets, the heat gained at the Earth's surface is released into the air above it. As the surface cools, it grows closer to the dew point, or the point at which the air would be considered "saturated." Once the temperature and the dew point are close enough together, fog begins to form. We often see this fog dissipate once the sun rises since the heating from the sun leads to the temperature growing further apart from the dew point. This, of course, wasn't the case this morning, as cloudy conditions that were in place wouldn't allow the rapid cooling effect needed for this type of fog to occur.
The type of fog that actually occurred is known as advection fog. In this setup, a stronger breeze moving over cooler ground is needed. This stronger breeze usually contains a warmer, moist air mass, which is being transported over the cooler surface. That warm air mass is then cooled by the ground below it, and this cooling process is what's needed to fully "saturate" the air. This saturation leads to the type of fog that Central Missouri saw this morning.
A similar setup can also occur over water. This process starts when winds over a body of water are moving over a cooler water surface to the shore. As the warmer, moist air moves over the cooler waters, the process of cooling the air mass to the point of "saturation" starts. This leads to fog formation over the body of water that then moves to the landmass it's being transported over.
No matter the type of fog, even just a little can be enough to drastically change visibility. On a clear day, visibility is expected to be around 6 miles. When even just a haze is added, visibility can be reduced to only 1-2 miles. In a foggy case similar to what occurred this morning, visibility can be reduced to less than a mile. This means that the time to react to things like changes in traffic or unexpected hazards drops significantly. This is why it is important to drive at slower speeds and with extra caution in conditions where visibility is reduced.
