Fog Funnel

July 25, 2014

Fog funnel

Photographer: Raymond Murphy
Summary Author: Raymond Murphy
Shown above is a photo of a fleeting funnel in the evaporating morning fog observed on a small lake near Saranac Lake, New York. This short-lived vortex was perhaps 15 ft (4.5 m) in height and moved slowly to the left. Generally, these vortices last for only for a few seconds. When the air is still and the warmth of the Sun has burned off (evaporated) all but the last bits of the morning fog that often blankets this part of the Adirondack Mountains, tube-like vortices can sometimes be detected in the mist. The evaporating mist isn't uniform but tends to gather into small cloudlets one to two feet high (about 0.5 m) that exhibit a surprising amount of vertical motion and even slight rotation. There are nearly a dozen of these cloudlets in the photo. Every once in a while, if the rotation is just strong enough to spawn a tube of spinning air that extends higher up, and if the temperature-humidity-pressure conditions are just right, condensation occurs at the wall of the tube, making it visible in the sunlight. Note also the crepuscular rays at right. Photo taken on June 23, 2014.