WATER CONDENSATION EFFECT CREATING EXTREME VORTICES IN BOEING 777
The cores of vortices spin at very high speed and are regions of very low pressure. To first approximation, these low-pressure regions form with little exchange of heat with the neighbouring regions (i.e.., adiabatically), so the local temperature in the low-pressure regions drops, too.If it drops below the local dew point, there results a condensation of water vapour present in the cores of wing-tip vortices, making them visible.The temperature may even drop below the local freezing point, in which case ice crystals will form inside the cores.
In simpler terms: These are low pressure condensation vortices due to the flaps edge, similar to the condensation “fog” on the upper wing. Wake vortices are larger in diameter, start at the wing tips, and are invisible in this movie because there is no low pressure and consequent condensation associated with them