Spicule radial velocities, and the coronal condensation mechanism of spicule formation

The time variations in the radial velocity of 90 spicules at various heights have been investigated on the basis of data acquired with a scanning device. The v/sub r/ curves vary synchronously over the full height range of a spicule; the mean value of v/sub r/ is approx. =10 km/sec. If spicules were to represent an upward flow of gas from below, serious difficulties would arise in explaining the mass balance of the corona. Various results indicate that spicules may be formed through condensation of coronal gas. Several supporting arguments are given for such a mechanism.