This time of year the valleys can start the day with a thick covering of fog. Sometimes around 9.00am what appears to be a bright and cheery start to the day can turn grey and slightly spookie as the sun retreats behind the thick rising fog. This transformation is rapid as a view like this can change within half an hour. Then as quickly as it rose, the fog gives in as the sun fights back. The day starts again!
Warm air from the Atlantic, cool air dropping off the mountains and probably something to do with dew point is why this happens. Dew point is our answer for all weather, temperature and humidity goings on that we don’t understand.
PS. If you want a larger view, click on the pic.