Continuous Snowfall Replicator

Abstract

A continuous snowfall replicator has been developed using the ?roll-on? Formvar technique to apply a continuous strip of liquid Formvar to a 35-mm motion picture film base. Snow crystals which settle onto the moving strip are replicated upon Formvar hardening, producing a continuous sample. The replicas are viewed by either a 20? microfilm reader or a 50?100 ? 35-mm projector. Computations are presented which give approximate crystal concentration figures (crystals cm?2) sampled with the instrument. Field tests during the Yellowstone Field Research Expedition #6, January 1966, produced continuous snow crystal concentration figures. Among the snowfall samples taken during the winter of 1965?66 near Climax, Colo., several recorded the change of crystal shapes, sizes, and concentrations through snowfall periods. Such information attests to the usefulness of continuous snowfall samples. The snow crystal replicas obtained with this instrument have significantly improved the Formvar replication technique.