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.

There has been increasing interest in quantifying methane emissions from a view towards mitigation. Accordingly, ground-based sampling of oil and gas production sites in the Permian Basin was carried out in January and October 2020. Ethane to methane ratios (EMRs) were quantified which may be used to distinguish emissions from particular sources, such as produced gas and oil tank flashing. The logarithmic mean EMR for 102 observations was 18 (±2)%, while source specific EMRs showed that sites where emissions were attributed to a tank produced much higher EMRs averaging 44%. Sites with other noticeable sources such as compressors, pneumatics, and separators had lower and less variable EMRs. Tanks displayed distinct behavior with EMRs between 10-21% producing CH4 emissions >30x higher than tanks with EMRs >21%. This observation supports the hypothesis that high emission rate tank sources are often caused by separator malfunctions that leak produced gas through liquids storage tanks.