ABSTRACT OF THESIS

The microphysical processes associated with the growth of clond and precipitation particles during two stable orographic storms are identi-fied in this thesis. A two dimensional steady-state model of airflow over an ideal mountain barrier is developed and used to define the loca-tion and rate of production of condensate available for liqaid water and ice particle growth in these two storms. A crystal trajectory model is also developed to determine origin levels and upwind location of cry-stals which impact on the mountain barrier. The major conclusions in this thesis concerning stably stratified storms in the northern Rockies are the following: a. The majority of clond liquid water in stably stratified oro-graphic storms exists in a narrow zone over the windward slopes of the primary barrier. Model results indicate that this zone extends verti-cally over the slope with maximum liquid water contents near the sur-face, On both days the model predicted location of the zone was in excellent agreement with aircraft observations. b, Droplet spectra in stable orographic cloud systems vary substan-tially depending on the air mass source region. On November 24s the overrunning air mass had modified maritime characteristics. Mean dro-3 plet sizes were near 15 p, droplet concentrations were 601cm and max-3 imum liquid water contents near.43 g/m. On November 26, the air mass behind the cold front had continental characteristics. Mean droplet 3 sizes were 6-9 p, droplet concentrations 2001cm and maximum liqai