Biomass Burning Smoke Influences Clouds over the Western U. S. | CU Experts

Small cumulus clouds over the western United States were measured via; airborne instruments during the wildfire season in summer of 2018.; 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. A number of complex and competing climatic impacts may result; from wide-spread reductions in cloud droplet size due to wildfires; prevalent across the region during summer months.

Twohy CH; Toohey DW; Levin EJT; DeMott PJ; Rainwater B; Garofalo LA; Pothier MA; Farmer D; Kreidenweis SM; Pokhrel RP

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