Every paragliding textbook says the same thing: sun heats ground, ground heats air, air rises. Fine. It’s also not the whole story. Sun is not the answer – it’s just the one you know.
The solar model dominates because most of the literature was written at latitudes where solar radiation genuinely is the main driver. But radiation and instability aren’t the same thing. Put cold air over a warm surface and you get lift whether the sun shows up or not. The engine is the temperature difference, not the light.
A friend’s flight log set this off. But the question had been sitting there for years – you don’t fly Norway and Greece back-to-back for over a...
