Advection fog/mist is when a moist air mass moves onto an area of the surface that is colder than the last and cools the air mass below dewpoint etc.
I found when I used to fly from LPL, often it was fogged in, localized around the airfield, but once clear of the area it was so different.
Yes, half of liverpool is coastal, so I assume the Mersey and Irish Sea will contribute to what was said above
It's frustrating when you tell someone (on a nice sunny day) that you can't fly cos of the weather, to which they reply "But it's a gorgeous day" - when in fact the vis is awful
