Dust and Organic Sea Spray Contribute to Cloud Freezing
A new study shows how dust from deserts and organic sea spray from tiny organisms in the ocean both play a role in freezing water droplets in clouds.
This study shows that for global atmospheric models to adequately simulate the concentrations of particles that trigger freezing of cloud droplets, they must include both desert dust, which has long been recognized as a source of freezing particles, as well as organic matter in sea spray, the importance of which has only recently been recognized.
While desert dust has long been recognized as an important source of freezing nuclei in the atmosphere, it has only recently been widely recognized that organic matter in sea spray may be another important player, especially over remote oceans. This research, by a team of researchers including a scientist at the Department of Energy’s Pacific Northwest National Laboratory, improves on earlier work by comparing simulated concentrations of freezing nuclei with a larger database of observations than was previously available, and by considering the implications of fluctuations in particle concentrations over time, as dust plumes come and go, for the importance of the two aerosol types.