Fall means…foggy mornings

BOWLING GREEN, Ky. – There are several types of fog. In South Central Kentucky, the most common type is radiation fog…

Radiation fog forms on clear nights when the wind is calm. 

The ground heats up throughout the day and begins to cool after the sun sets. 

When the humidity is high enough in the lower atmosphere and the cool, rising air passes through the layer of moisture…

It causes the rising air to cool even faster. As the air continues to cool, the amount of moisture in the air increases. 

The moisture in the air becomes fog. Another type of fog we often see in the area is steam fog.

You can thank our abundant lakes and rivers for this type of fog.

Lakes and large rivers hold heat longer than the air around them. When the colder air moves over the warmer water, water evaporates from the river or lake, increasing the amount of humidity just above the surface of the water.

That lowest layer of the air warms thanks to the warmer water below it.

The moist layer of air rises and the water turns to fog but may look like steam rising off a pot of boiling water.

The third type of fog we see happens when we get rain and it’s known as precipitation fog.

Precipitation fog develops when a layer of warmer air moves in close to the ground during rainy conditions.

The rain warms up as it falls through that layer of air and some of the rain even evaporates.

The evaporating rain raises the humidity of the warm air layer and as the air gets fully saturated, fog forms.