10-1/2 x 9"
Pen & ink, watercolor

Fog I

Fog is cloud on the ground. Like all cloud, fog is made of tiny water droplets or ice crystals — too tiny to see and too tiny to be much affected by the force of gravity. The water droplets form when saturated air — air at its dew point — cools. You have seen this happen when, after your shower, saturated air comes in contact with the cold glass of the bathroom mirror.

On a clear night, the ground and the air just above it give up their warmth. If the air is humid enough, fog will form. If a light wind mixes the layers of air, the fog will deepen and the fog itself will lose heat, become heavy, and pool in the low places.

Fog also forms when evaporation from water, swampy ground, or warm rain saturates the air, and the air cools a little.