Brian, the Met Office answer to your question would be 'Hill Fog' which they forecast regularly in UK, usually with a visibility in hundreds of metres.
If you live in the SW of UK, the moist Tropical Maritime airmass often produces very low cloud along with 30 -40 kt winds - to an observer at sea there is a low cloud base - an observer on a 200' cliff can see less than 1000m because he is in cloud but it looks just like fog.
There is no difference between fog and cloud, other than what triggers the condensation process - it all depends on where you are viewing the cloud/fog from.