photo #5569786

Alan Bevis (Member 41,562) watched a small boat roll on the swell of Swanage Bay, Dorset, England as a type of fog known as sea smoke rose from the water’s surface. The water of the bay was likely warmer than the chill December air. Moisture evaporating off the water’s surface would have warmed the low air and encouraged it to float up in wisps through the cooler air above. Soon it would have cooled enough once more for the moisture to condense back into droplets of fog. The still air in the bay, sheltered from the gentle northerly breeze, would have meant the evaporation fog stayed in separate wisps. Beyond the small boat, out over the open water, a bank of far thicker fog had appeared. The marked difference was likely due to the breeze beyond the bay stirring the low air. This would have helped spread out the fog and feed it by encouraging the evaporation off the surface. Clearly, the skipper of that dinghy knew to stay in the sheltered visibility of Swanage Bay’s sea smoke and well away from the thick blanket of the open water.