Interpretation of Foil Impactor Impressions of Water and Ice Particles

Abstract

Impacts of hydrometeors on aluminum foil over a grooved backing, as in standard airborne foil impactors, have been produced in the laboratory using a modified crossbow to achieve aircraft speeds. The purpose of the work was to test the ability to distinguish the phase of the hydrometeors from the nature of the imprints. Solid, spherical ice pellets (frozen drops) and drops of slush leave impressions that are often indistinguishable from those left by liquid drops, at sizes below about 3 mm diameter.