Large oil refineries emit heat, vapor, and cloud condensation nuclei (CCN), all of which can affect the formation of cloud and precipitation. The Factor Separation (FS) technique is applied to isolate the net contributions of waste heat, vapor, and CCN to the rainfall of a cumulus developing in the industrial plume. The mutualinteractive contributions of two or three of the factors are also computed. The model simulations indicate that the sensible heat provides the major stimulus for cloud development and rain formation. The pure contribution of the industrial CCN is to enhance the condensation causing an increase in the mass of total cloud water. The contributions arising from mutual interactions among two or three factors are quite large and should not be neglected. Particularly, the synergistic interaction of the sensible heat and pollution effects contribute towards the accumulated rainfall.

Introduction

There is considerable interest in the effects of large electrical power plants and oil refineries on meteorological phenomena. Preferential cumulus formation has been observed above electrical power plants and oil refineries (Auer, 1976). Hobbs et al. (1970) reported that in regions adjacent to or downwind of the Port Townsend paper mill (Washington State, USA) the annual rainfall recorded was 30% greater than the rainfall from nearby stations. This dramatic increase in annual precipitation is likely caused by the presence of the paper mill. Hobbs et al. speculated that the enhanced rainfall might be attributed to the large and giant CCN emitted from the paper mill into the pollution plume. Support for this hypothesis came from Eagan et al.'s (1974) study.