Climate modellers know less about cloud formation than they thought they did, according to new research.
There is enough known about cloud formation that replicating its mechanism has become a staple of the school science project scene. But a new study by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) reveals that much more is going on at the microscopic level of cloud formation than previously thought.
The scientists determined that organic molecules effectively depressed the surface tension of the water, allowing for more efficient formation of bigger cloud droplets. “Conventional wisdom says that the water solubility of the aerosol is the key factor in the formation of cloud droplets,” said study senior author Kevin Wilson, the deputy director of science at Berkeley Lab’s Chemical Sciences Division.
“The more easily a particle dissolves in water, the easier it is for a cloud droplet to form. What we’re finding is that relying upon solubility alone doesn’t always work. Our study suggests that what the aerosol is doing at the interface with water is what matters in accurately predicting whether it will go on to form cloud droplets.”
The findings, to be published in the March 25 issue of the journal Science, could improve the accuracy of climate change models that predict the potential cooling effect of reflective clouds based upon the particles in the air.
“Accurately describing the connection between the chemistry of aerosol particles and the formation of cloud droplets remains difficult, and it is a key challenge for models to correctly predict climate,” said Wilson. Wilson worked with study lead author Christopher Ruehl, who did the research while he was a postdoctoral scholar; and co-author James Davies, a current postdoctoral scholar at Berkeley Lab.
Full Phys.org report: Researchers find new mechanism to explain the birth of cloud droplets
The report then goes on to look into the technicalities in more detail.
“The role of inorganic and organic aerosols in cloud formation has been a highly contentious issue that’s been argued about for many years,” said Wilson. “Based on the paper’s findings, I would say that these surface interactions play a central role in cloud droplet formation, and that they should be considered in climate models.”