Where it comes from, how it happens and what it's correctly called are all mysterious topics here at the Bega District News, so we gave ourselves a crash course in weather conditions this morning and are here to clear up the issue.

Fog, clouds, sea-mist - the difference is all in the eye of the beholder.

All three are caused by water vapour in the air being withing 2.5 degrees of the dew point. Aside from the obvious - that clouds are high in the air, while fogs and mist are closer to the ground - there are some more subtle differences.

"Fog" is more dense than mist, so reduces visibility to a greater degree. But the point where fog ends and mist begins is a little hazy.

For aviation purposes, fog has a visibility of less than one kilometre.

However, for drivers travelling at much slower speeds, fog reduces visibility to less than 200 metres.

Mist is everything with better visibility than fog.

Fogs and mists can be described by how they form. So "sea mist" is a light fog caused by cold air passing over warmer water, or moist land, and often includes particles of salt as well as water.