Biomass burning smoke and its influence on clouds over the Western U.S.

Statistics of the sampled clouds are presented and compared to smoke aerosol properties. Cloud droplet concentrations were enhanced in regions impacted by biomass burning smoke, at times exceeding 3,000 cm(-3).

Images and elemental composition of individual smoke particles and cloud droplet residuals are presented and show that most are dominantly organic, internally mixed with some inorganic elements. Despite their high organic content and relatively low hygroscopicity, on average about half of smoke aerosol particles >80 nm diameter formed cloud droplets. This reduced cloud droplet size in small, smoke-impacted clouds.