A significant portion of ice accreted on structures in freezing precip
itation or sea spray is in the form of icicles. Estimation of ice load
s is, therefore, accurate only if we know the size and spacing of icic
les. In this paper a theory and results of wind tunnel experiments on
the spacing of icicles formed at moderate wind speeds are presented. T
he results show that icicle spacing on elongated horizontal objects or
iented perpendicular to the wind direction is 2 cm regardless of the g
rowth conditions.