Book Description

This paper is concerned with the problem of visibility at sea and fog over the sea. Restrictions to visibility in general are discussed and suspended moisture is related to low visibilities at sea. Fleet Numerical Weather Facility at Monterey produces a field of the difference between the vapor pressures of the sea and air. This field is used as a humidity index to determine the moisture in the air and is related to visibility. A total of 1100 data points from the North Atlantic were analyzed and an attempt was made to produce a linear regression equation. The regression equation proved to be most inaccurate in the area of low visibilities. A scattergram of visibility as a function of air temperature and the vapor pressure difference revealed a significant relationship. Using this relationship it is possible to forecast visibility and fog probability.