Meridional Alignment of Tropical Cirrus Clouds

Abstract

A NUMBER of underlying misconceptions must be pointed out in the recent suggestion by Kellner¹ that meridional alignment of tropical cirrus clouds results from geomagnetic interactions with the nuclei inside the cirrus particles. First, it is not an established fact that cirrus ice crystals are actually nucleated by dusts of meteoritic origin, although this is an interesting hypothesis that was introduced some years ago by Bowen². Secondly, if any meteoritic dusts do serve as nuclei at cirrus-levels it would be most unlikely that those of iron–nickel composition would be important. Rather, it would be the stony component that might conceivably offer epitactic surface nucleation sites for ice growth. Actually, direct tests³ of nucleating efficacy of stony meteoritic particles indicate much lower nucleation efficiency than silicate dusts of terrestrial origin, leaving even that portion of the meteoritic dust an unlikely source of cirrus nuclei.