The Big Smoke

I know Wellington is a teeny city but from some angles it can feel like it's an urban jungle out there.

What's the difference between mist and fog?

It's a foggy/misty morning here in Christchurch and as I was leaving the house I noticed that I had described it as a "Misty morning" whereas Liz has used the word 'fog'. So, what's the difference?

(It's such questions that the Interweb/Googley-knowledge-finder was built to answer)