Fog
Radiation Fog Explained: Clear Nights, Calm Wind, and Morning Visibility
What radiation fog is, why it forms on clear calm nights, and why it often disappears after sunrise.
Quick answer: Radiation fog forms when the ground cools at night and chills the air near the surface to saturation.
Best setup
Clear skies, light wind, moist ground, and long nights help the surface cool efficiently.
The air near the ground can become saturated, forming fog.
Morning changes
Sunlight warms the ground and mixes the lower atmosphere, often lifting or dissipating the fog.
In winter, weak sun and snow cover can make fog last longer.
Forecast clues
Look for calm winds, high humidity, recent rain, and overnight cooling.
Low-lying areas often fog first.