Airborne microbes are of interest to atmospheric scientists, because they could play a role in forming ice that may impact weather and climate, and long-distance transport of the bacteria could also be of interest for disease transmission models. Participants discuss their research characterizing the bacteria present at different altitudes in the troposphere and genetic mechanisms by which microbial cells could reach and remain at high altitudes in the atmosphere and initiate the formation of water droplets or ice crystals, which is important for cloud formation.