https://phys.org/news/2018-10-drones-soar-clouds-ice-formation-effect.html

Aerosols result from human activities or occur naturally as dust, pollen, fungal spores, bacteria or marine organics. "We investigated the importance of biogenic (natural or pre-industrial) versus anthropogenic (human-made) emissions for aerosol-cloud interactions in regions that are key regulators of the Earth's climate, such as the Amazon rain forest or the Arctic," says project coordinator Professor Ulrike Lohmann, Professor for Atmospheric Physics at the Institute for Atmosphere and Climate Science, ETH Zurich, Switzerland.

"Very little data is available for many of these regions, particularly over oceans," she notes. "To start with we wanted to know what fraction of the cloud is composed of water droplets versus ice crystals and then how this was affected by aerosols."