What is reported as sea fog is sometimes just coastal fog. Often there
is fog along the cliffs near Land's End, then lovely blue sky until
you get to Scilly, which have fog banks all around.

www.sennen-cove.com/today2.htm has good pic of coastal fog starting to
form as the air rises up the cliff. Aerial view of coastal fog at the
same location at www.easterling.freeserve.co.uk/wpage6.html (go to the
bottom of the page.

Graham
Penzance