Next imagine our two jumpers jumping from a tethered balloon in a wind. Because the balloon is tethered, the groundspeed is zero. The jumpers drift with the wind in freefall and also when under canopy. Note that the light trails are the same (dashed line). However, the smoke trails are separate and distinct for the two jumpers, because they drift downwind. Separate smoke trails mean each has his/her own column of air. Their separation is satisfactory despite the zero groundspeed of the jumpship.