Autumn Mornings Bring Valley Fog
Downloads November 8, 2026, Terra MODIS JPEG (3.02 MB) November 8, 2026, NOAA-20 VIIRS JPEG (3.29 MB) References & Resources NASA Earth Observatory (2018, October 26) It ‘ s Valley Fog Season.
Key points
- NASA Earth Observatory / Lauren Dauphin morning afternoon A natural-color satellite image from the morning shows white fog filling a branching network of river valleys, surrounded by brown and green terrain.
- As nights lengthen, the ground has more time to radiate away the day’s heat, and the air just above it cools to the dew point —the temperature at which air becomes saturated and water vapor begins condensing into the tiny droplets that make up fog.
- NASA Earth Observatory / Lauren Dauphin A false-color satellite image from the afternoon shows the same area clear of fog, with rivers and lakes in dark blue winding through bright green vegetation.
National Weather Service (2023) Weather in Action: Valley Fog.
Forecasters reported locally dense valley fog that morning.
Additional details
- Notice the fog filling the branching valleys across part of the Appalachian Plateau in eastern Kentucky and southwestern West Virginia.
- Dense fog had also blanketed a wider part of the region earlier in the week, prompting advisories for hazardous travel conditions.
- Because cold air is denser than warm air, it flows downslope and pools in valleys, so fog tends to form there first.
- Rivers and streams that run along many of the valley floors add to the effect by supplying extra moisture.
- By afternoon, they had faded, leaving clear skies over the autumn landscape.
How this summary was made: extractive summary — built from the sources' own reporting. It is drawn only from the reporting of the sources listed below — read the originals for full detail. How we summarize →
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