The dense fog that developed Wednesday and Thursday morning of this week is known as radiation fog!
Radiation fog is a very common type of fog throughout the United States and even more likely to occur in the fall and winter. It forms overnight as the air near the ground cools and stabilizes. When this cooling causes the air to reach saturation, fog will form.
See video of a foggy Downtown Cleveland Thursday morning:
Fog will first form at or near the surface, thickening as the air continues to cool. The layer of fog will also deepen overnight as the air above the initial fog layer also cools. As this air cools, the fog will extend upward.
Radiation fog is also more likely in sheltered valleys, near bodies of water and when there is minimal wind. Wind would disrupt the formation of radiation fog. Radiation fog is usually patchy, tends to stay in one place and goes away the next day under the sun’s rays. Thicker instances of radiation fog tend to form in valleys or over calm bodies of water.
It has nothing to do with nuclear radiation, it’s named as such because it forms when heat absorbed by the surface during the day is radiated into the air.
This is not the only type of fog though! There is also advection fog, lake/sea fog, mountain/valley fog and freezing fog!
A fog advisory can be issued by the National Weather Service when widespread dense fog develops (like Northeast Ohio saw the last two mornings). When this happens, visibilities frequently drop to one-quarter of a mile or less. These conditions make travel difficult. Take extra caution when on the road and use your low beams, or avoid driving if possible.
