The Twinkling of Distant Light-points

Abstract

REFERRING to Prof. Conrad's letter on “The Twinkling of the Stars”, etc., published in NATURE of March 8, it may be of relevant interest to refer to the twinkling of the lights of coastal towns, as seen from a few miles at sea, on dark nights when the atmosphere is clear. Such pulsations are very conspicuous at times. I was under the impression that differences in the densities of air-layers produced the effect, but might not the wave-movements of the sea produce corresponding oscillations in the air above it, thus creating disturbances which would destroy optical continuity? Such twinkling of artificial lights at, practically, sea-level cannot be due to nitrogen-dust.