Soleoy by Visual Reference
The consensus from our corner of the bar is that for the purposes of the VFR rule:
1. Fog is not cloud; it doesn’t have a ‘Latin’ sounding name and it is usually in that part of a METAR that covers visibility not cloud - so you are not in cloud at 1,000 metres visibility.
2. Our regulator has approved an Ops Manual limit of 600 metres viz for VFR Public Transport so they don’t think that 600 metres viz is ‘in cloud’.
3. That you are no longer ‘clear of cloud’ (and therefore no longer VFR) when you are unable to fly solely by visual reference.
Therefore when you are on the top of a mountain (below 3000 feet or whatever the rule is in your area of the world) and have been living out of a tent for a month you can gauge all these weather rules and ceilings for VFR quite simply by asking yourself whether you can fly down the mountain, and not bump into anything, solely by visual reference.
Not a great idea to push the limits so close but as many of us know the real world requires us to do it sometimes.