Hudson Valley fog environments

Abstract

Observations of 14 cases of radiation fog in the Hudson River valley in New York State are presented. Estimates of the surface and boundary layer heat budget are presented. Two new phenomena are identified: 1) A jump in specific humidity occurring during the early evening transition that shortens the time required to reach surface layer saturation; and 2) along-valley jetlike winds with maxima near 100 m altitude are shown to be frequent and their occurrence is associated with a threshold value of the along-valley surface pressure gradient. Such jets appear to have an important influence on deep fog, increasing or decreasing its likelihood depending on the sign of heat and moisture advection they associate with. -from Authors