What's the difference between mist & fog?

kindredspirit

kindredspirit

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What\'s the difference between mist & fog?

Now I know there's no "technical difference" but we actually perceive that there is a difference as we generally refer to either mist or fog.

Could anyone give a specific definition of mist as opposed to fog?

( P.S. I know the technical definition of both, i.e. vis under 1,000 km.)
 
Re: What\'s the difference between mist & fog?

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( P.S. I know the technical definition of both, i.e. vis under 1,000 km.)


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1,000 metres perhaps?
 
Re: What\'s the difference between mist & fog?

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Could anyone give a specific definition of mist as opposed to fog?

( P.S. I know the technical definition of both, i.e. vis under 1,000 km.)

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but that is the definition, fog is just a denser mist
 
Re: What\'s the difference between mist & fog?

A WAG...

The size of the water droplets??? If they're big enough to fall, it's a mist...if they just hang in the air, it's fog???
 
Re: What\'s the difference between mist & fog?

If visibility is less than 1000m and relative humidity is over 95% (i.e. air almost saturated with water) then its FOG.
However, if vis. is between 1000m and 10km, and RH is over 95% then its MIST.
If vis. is less than 10km and RH is less than 95% its HAZE.
These are the met. office definitions, we covered it in meteorology very recently!
It also must be pointed out that if vis. from an observing station on one side is 40+ km, but is only 500m with over 95% RH on the other side, its still recorded as fog.
 
Re: What\'s the difference between mist & fog?

So the Met Office say that if the fog is further away or less dense then it's mist.

I think the size of the water droplets in the mist/fog should also play a part in the definition. You get wetter in a mist than in a fog, don't you?

And in a mist you can sometimes see over the top but in a fog you can't.

Just wondering because somebody asked me this today.
 
Re: What\'s the difference between mist & fog?

Simple - less than 1000m it's fog. Above 1000m it's mist. Both are caused by the condensation of water vapour into droplets.

Haze is nothing to do with water vapour, being caused by dust, sea salt, etc.
 
Re: What\'s the difference between mist & fog?

... and don't forget all the other possible obscurants such as smoke, dust and sand, and wond-blown sea spray, just to give a few examples from the one big met book I've got handy!

It also mentions ice fogs, which I had forgotten about, but are found in -20degC or less in polar regions.
 
Re: What\'s the difference between mist & fog?

Mist isn't as funny as fog.

If Michael Fish had said "I'm sorry there's no M in mist" would we have laughed?
 
Re: What\'s the difference between mist & fog?

Sound the same to me but different.

While on weather and viz.....anyone know what the expression 'smoke' means. Have in past heard this used on shipping forecast but can't find it referred to anywhere
 
Re: What\'s the difference between mist & fog?

Vague recollections from a course a long time ago...

Smoke may be reported when the visibility is less than 10km, relative humidity is less than 95%, and there is an obvious source of the smoke.

It's most serious with big forest fires, and light winds and temperature inversions cause it to hang around.

Smoke also provides loads of hygroscopic nuclei - and you ALL know what that means!
 
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