A clear morning with a brisk sub-zero wind over the water is ideal for sighting steam devils.
There was only a gentle wind two days ago and the devils were not as grand as on some earlier occasions. Yet, as I get to see them play for only about a half hour every three years, and each devil lasts less than a minute, these ones were worth recording.
Steam devils are vortices in the wind made visible by the droplets of steam fog (just as a dust devils are made visible by tossed-up dirt). On a lake covered by steam fog, the devils can form almost anywhere, but are most easily seen when backlit against a dark background.
A steam devil is seen just as it forms.
Sometimes, a steam devil can extend tens of metres above the surface.
The best contrast is between the yellow sunlit devil and the dark bluish mountainside.
Alistair, so do ‘steam devils’ occur over water also in summer, the way dust devils do, albeit then invisible for want of steam? If so, I suppose they must have some other name unknown to me, but no doubt familiar to you. Thoughts?
Trevor, the answer depends upon how literally one interprets the name, devil. Certainly vortices in the wind, called whirlwinds, can occur in any season. They often form when there is strong convection over a surface and a brisk wind. However, the word, devil, comes from the Greek and means to throw (Satan gained it by throwing slander). Presumably, it is not just a whirlwind that prompts the name, but something has to be thrown. So, we may talk about dust devils, snow devils, and steam devils (short for steam-fog devil), depending upon which thing is lifted and tossed. Snow devils are more likely to appear when a strong wind passes a salient edge, such as a cornice.
Thanks Alistair. So a ‘devil’ in this sense is a whirlwind made visible by whatever it happens to carry – more or less the way Tolkien’s Ringwraiths are made visible by the clothes they wear. Strictly speaking, I suppose one might also speak of leaf devils (in autumn), trash devils (in urban areas) and so on. I like this.
Trevor, yep.