>For example you can't look for the Sun if its cloudy. //
I do - one can often tell where the brightest part of the sky is even on an overcast day; knowing roughly the time and season (for a known geography) then gives a rough direction. I read a report that polarising sunglasses help this too but I've never actually tried. With me it's sometimes more of a perception that the sun is in such a direction whilst I can't really make out that part as [particularly] brighter.
I do - one can often tell where the brightest part of the sky is even on an overcast day; knowing roughly the time and season (for a known geography) then gives a rough direction. I read a report that polarising sunglasses help this too but I've never actually tried. With me it's sometimes more of a perception that the sun is in such a direction whilst I can't really make out that part as [particularly] brighter.