Biological Particles (Bacteria and Fungi) in Thunderstorms

Aerosol particles play an important role in cloud formation, affect cloud lifetime, and precipitation formation processes. Ice nuclei concentration greatly influence precipitation development in cold clouds. Biological particles (bacterial and fungi) are important atmospheric ice nuclei; however, there have been few measurements of the types of biological particles in the upper troposphere. A 2019 research project (CapeEx19) in Titusville, FL during the summer 2019, with the North Dakota Citation Research Aircraft provided the opportunity to obtain upper tropospheric measurements of particles in and around thunderstorms. Filter samples were collected from 9.14 km (30,000 ft) to 12.19 (40,000 ft) MSL while flying in and around cirrus cloud anvils. Each sample was kept in a closed container until DNA sequencing to determine species. Identification of fungi and bacterial species is done using ribosomal internal transcribed spacer sequence ITS for fungi and 16S ribosomal RNA-encoding DNA for bacteria. Species identification enables us to determine the atmospheric source by relating the species found in the cirrus anvils to their locations on the Earth’s surface.