Steam fog – smoke over water

Have you ever seen a smoke moving lazily on the surface of a lake? And no, we’re not referencing the hit song Smoke on the Water from Deep Purple here! Especially because that smoke came from a burned down casino, while we want to talk about a smoke that requires no fire. Smoke floating over water is a completely natural, even if pretty uncommon occurrence – this phenomenon is called sea smoke or steam fog. But where it comes from and when can it be seen?

What exactly is a sea smoke?

First of all, we must start with what fog and foggy weather is. Fog is a type of low-laying cloud composed of very tiny (about 20 millionths of a meter!) water droplets suspended in the air. And steam fog is a type of fog, that forms when very cold air mixes with a thin layer of warm air situated right above the even warmer water. The cold air causes the warm air to cool, which in turn causes water vapor to condense out. It’s pretty similar to what happens when you pour a hot cup of tea – the steam above it is formed in similar fashion as steam fog.

Seeing smoke like mist over water is usually possible in very cold climate, as it requires very low air temperature to occur. It’s common in places like the Arctic and Antarctic, where it can be spotted above patches of water formed in the sea ice.

If the weather is windy, smoke over water may start forming tornado-like columns, called steam devils. Although much less destructive, they can be rather impressive – some of its columns can reach up as high as 95 ft (~30 m).