SALT NUCLEI IN MARINE AIR AS A FUNCTION OF ALTITUDE AND WIND FORCE

TLDR

Bursting air bubbles in white caps on the open sea are a major source of salt nuclei, with the sea surface contributing more during average winds than previously estimated. Samples were primarily collected near the Hawaiian Islands. Sea‑salt particle numbers and sizes vary with altitude, location, and time, with larger particles increasing most near cloud base in proportion to wind force, and similar patterns observed across Hawaii, Florida, and South Australia.

Abstract

Large differences are shown to occur in the numbers and sizes of sea-salt particles in marine air over the sea as the altitude, position, and the time of sampling are varied. Increases in the amount of air-borne salt near cloud base are related to increases in wind force at the sea surface. The greatest proportionate increase in particle number occurs at the large end of the weight range. Most of the samples reported here were taken near the Hawaiian Islands. The differences in nuclei number and size with increasing altitude in the lower atmosphere are similar in pattern in Hawaii, Florida and South Australia. It is suggested that bursting air bubbles in “white caps” on the open sea are a major source of the salt nuclei, and that a greater portion of the sea surface may act as a source of these particles during average winds than might be judged from the relatively small area usually covered by white caps.