Combinations of clear nights, very light winds, and a humid stable air mass give (fall, winter and spring) conditions which lead to the formation of overnight radiation fog.

As the earth’s surface cools due to nighttime radiation, the humid air in contact with the surface cools below its dew point.  The water vapour in the air then condenses to form fog.  The fog usually dissipates when morning sunshine warms the air from above.

Here are some photos of morning radiation fog:

Westbound Canadian National freight reflected in the Still River across from Gerry’s place on Riverside Drive (Hwy 526).

Still River from Riverside Road near Jane Street.

Still River from Old Legion Road…

The fog was being “burned off”, evaporated into water vapour, by the morning sun as we looked out over Byng Inlet from in front of Keith’s place on Riverside Road…

At a gentle anchor on a still morning …

St Amants new docks are brilliant in the morning sun….

On the following morning, under similar weather conditions, we drove along the Forest Access Road, encountering these scenes of the morning sun illuminating radiation fog.

The fog persisted in low areas as it evaporated on higher ground…

When side-lit the fog occasionally showed ground level crepuscular rays …

Even in bright morning sunshine haze remained over swamps and valleys.

Finally the fog cleared, leaving dew-moistened autumn leaves for the photographer to enjoy and share.

There is a lot of free advice on the internet about autumn photography.  These suggestions seem helpful for enthusiasts.

The frontal passage on the last weekend in September will encourage migrants to get on with their journey.   Mary Holland reports the unusual numbers of Painted Ladies travelling through New England this year.

EDIT:  See Correction to Painted Lady Identification.

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