Fog vs Mist

This morning, as we surveyed the start of what looks to be a significantly extended period of fog, Andy asked me if I knew what the difference was between fog and mist was. Pausing for a moment I had to conclude that I didn’t and had never really considered the possibility that they were distinct things. After some random speculation that fog was very low clouds while mist, um, probably wasn’t wasn’t I said I’d look it up and get back to him.

In a satisfyingly long entry Wikipedia confirms that fog is “a cloud in contact with the ground”. However, the entry for mist is somewhat on the scrappy side and, alongside defining it as “a phenomenon of small droplets suspended in air”, states that “the only difference between mist and fog is visibility”. The implication is that mist can be created from a number of sources, such as a fine spray of water from a hose or steam from a sauna whereas fog can only be formed as clouds are formed, in other words by the weather.

So, to summarise…

If it’s a real pea souper and you can’t see shit, it’s foggy.

If there’s a lot of moisture in the air but you can still see a reasonable distance, it’s misty.

It can be misty if there aren’t any clouds in the air should you be in an environment where cold air is warming up, ie at dawn. Or standing next to a boiling kettle in a cold room.

Mist can be caused by low hanging clouds but they’ll be really wimpy ones. If they’ve got any substance to them of worth then it’ll be fog.

You’re welcome.