Kevin Palmer Photography captured this image of a steam devil – a small whirlwind over water made visible by fog drawn up into the whirl – above Yellowstone Lake in Wyoming. He wrote:
After a fresh snowfall, fog had formed all across this lake … While steam devils are not rare in Yellowstone, this one was unusual because of the length of time it lasted. It spun away on the opposite side of the lake for about 15 minutes in nearly the same spot. Most of the time they last no more than a couple minutes. There is also a second, very skinny funnel to the right of the main one.
Steam devils are rare, but they may form over large lakes and oceans during cold weather, if the water below is still relatively warm. Yellowstone National Park is known for its steam devils, not in Lake Yellowstone particularly, but in hot springs in the park, which produce them often and sometimes daily, even in warm weather. The reason is the temperature difference between the air, which may be warm, but not as warm as the very hot water in the geysers.
Thank you, Kevin!