Marine Fog Droplets and Salt Nuclei -Part 11

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  • 1 Department of Oceanography, Hawaii Institute of Geophysics, University of Hawaii, Honolulu 96822
  • | 2 Atmospheric Sciences Research Center, State University of New York at Albany, Albany, NY 12222
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Abstract

In Past 1 of this fog study, the distribution of water with number and size of drops in some New England marine advection fogs was shown to be related to the distribution of number and size of salt particles found in marine air. It was indicated that in saturated air the calculated amounts of water condensed on the salt particles produced water distributions as a function of drop size much like distributions observed in numerous advection fogs. The results suggest that salt particles play an important role in the initiation and growth of marine fogs.

In the present work, photomicrographs of drops and of drop salt nuclei from several New England marine fogs are studied. The results confirm the conclusions of the first study, demonstrating even more clearly the direct relationship of drop weight to nucleus weight. The fog drops must have grown in supersaturated air, because in almost all of them the salt concentrations were below the equilibrium values for saturated air. However, the number and sizes of the salt nuclei in the air and fog support the idea that the fogs probably developed first as moderate haze-droplet fogs in saturated air (i.e., relative humidity 100%). A temperature-mixing ratio diagram is used to explain how saturation may be sustained by mixing, for the time intervals required for these haze-drop fogs to develop.

Abstract

In Past 1 of this fog study, the distribution of water with number and size of drops in some New England marine advection fogs was shown to be related to the distribution of number and size of salt particles found in marine air. It was indicated that in saturated air the calculated amounts of water condensed on the salt particles produced water distributions as a function of drop size much like distributions observed in numerous advection fogs. The results suggest that salt particles play an important role in the initiation and growth of marine fogs.

In the present work, photomicrographs of drops and of drop salt nuclei from several New England marine fogs are studied. The results confirm the conclusions of the first study, demonstrating even more clearly the direct relationship of drop weight to nucleus weight. The fog drops must have grown in supersaturated air, because in almost all of them the salt concentrations were below the equilibrium values for saturated air. However, the number and sizes of the salt nuclei in the air and fog support the idea that the fogs probably developed first as moderate haze-droplet fogs in saturated air (i.e., relative humidity 100%). A temperature-mixing ratio diagram is used to explain how saturation may be sustained by mixing, for the time intervals required for these haze-drop fogs to develop.

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