Thinking about fog on the Solway

This started with an observation. We drove out of sunshine in Kirkbride and into mist at Bowness-on-Solway. Then we headed along to Campfield Marsh and came back out of the mist. Looking back, there was mist over the water but not over the tidal sands. Bowness is where the channel comes close to land and would thus get the conditions that exist over water. I'm guessing that the humidity must be higher over the water. The air above the water shouldn't be colder than over land. The temperature of the sea does not vary very much because it has such a big thermal mass. In fact, sources suggest that the air over the sea should be warmer than over land on a clear night. http://www.metlink.org/other-weather/science-in-the-sky/fog/ The suggestion is that cold air from land moves out over the sea and puts the water vapour below the dew point. I'm guessing that what I saw must be due more to humidity than temperature.