Once the spider is airborne, it will rise as long as the wind's vertical vector component exceeds the system's free-fall terminal velocity. Relative air velocity affects the length of the ballooning silk filament and travel speed. Spiders attached to short filaments in strong winds travel further and faster than the same spider attached to a long filament in slower winds. Ballooning spiders have been seen at altitudes of more than 4000 metres and have been carried more than 300 kilometres. The threads reduce fall speed by increasing drag, not by increasing lift.
Longer threads induce slower fall, as has been measured in the laboratory.
Upward and downward movement while airborne is caused mainly by atmospheric turbulence the balloonists simply fall down.