Significant quantities of pollen were found to
be airborne at twice the canopy height when the rms values
of vertical velocity fluctuations, sw, exceeded 0.15–0.2 m s1
which was of the same order as the estimatedmagnitude of
the still air settling velocity of spherical particles with size
and density of corn pollen. The fraction of pollen transported
upwards from canopy height to twice this height, increased
with increasing sw.