What is rare Arctic sea smoke - and why has it formed on this South West beach?

  • Watch: Arctic sea smoke in Cawsand, Cornwall (Tony Lewis)

A layer of Arctic sea smoke has appeared over the water at Cawsand in Plymouth - but what's caused it?

Mist and fog are types of weather that can form at any time of the year. They're essentially a cloud that forms near the surface instead of way up in the sky.

As long as the air temperature is low enough, there's a source of moisture and winds are light there's a chance of fog.

Arctic Sea Smoke or Steam Fog across Cawsand, Cornwall Credit: Tony Lewis

Some types of fog are rarer than others, and the one pictured here is called "Arctic Sea Smoke" due to its wispy appearance as it drifts around.

The 'Arctic' part of the name is because that's typically where the air is cold enough for this to form, so to see it over waters in the West Country is quite something.

When the air is seriously cold, as it was in mid-December 2022, it can cause the moisture directly above the relatively warm sea surface to condense and turn into mist. Light winds cause it to softly swirl and give the appearance of smoke on the water.

It's a very similar process to steam that forms after you've run a bath. The air directly over that hot water meets the cold air in the bathroom and creates all that condensation in the air.

It's another reason why this rare type of mistiness is often called "steam fog", so, keep your eyes peeled as wintry weather can sometimes offer up something out of the ordinary.