How come it's always sunny on the aerial photos no matter what part of world you look at? I live in the UK, which is notorious for its variable weather in different regions, yet in Google Earth the weather is good all over the UK.

Could this be because each city in a country is not photographed on the same day but only on sunny days and then “spliced” together to give the illusion of continuity (as is presumably done to avoid the appearance of night on the photos)?