Cloud droplets mingle with dry air and evaporate as clouds encounter clear skies. Researchers from the University of Gothenburg have successfully captured the behavior of a model in a recent study. In the end, this could result in future climate modeling that is more precise.
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The climate of the world is significantly influenced by the clouds in the sky. In addition to creating precipitation and offering protection from the sun, they also serve as huge reflectors, preventing the Earth’s heat from radiating outward, a phenomenon known as the greenhouse effect.
Although clouds have been studied for a long time, they are one of the biggest sources of uncertainty in climate models. This is because there are so many factors that determine how the clouds affect radiation. And the turbulence in the atmosphere means that everything is in constant motion. This makes things even more complicated.
Bernhard Mehlig, Professor of Complex Systems, University of Gothenburg
Focusing on the Cloud Edge
A recent statistical model that explains the interactions between the quantity, size, and vapor of water near the turbulent cloud edge is presented in a study published in Physical Review Letters. Since water droplet dispersion influences how clouds reflect light, it is significant.
The model describes how the droplets shrink and grow at the cloud edge when turbulence mixes in drier air.
Johan Fries, Study Co-Author and PhD Student, University of Gothenburg
The most crucial factors have been determined by the researchers, and their model has been constructed appropriately. To put it briefly, the model considers the turbulent motion of the droplets as well as the principles of thermodynamics. The model explains the findings of previous numerical computer simulations and agrees well with them.
The Importance of Evaporation
Mehlig added, “But we are still a long way from the finish line. Our model is currently able to describe what is happening in one cubic meter of cloud. Say, fifteen years ago it was only one cubic centimeter, so we are making progress.”
Policymakers place a lot of weight on IPCC climate models when debating climate change. Nonetheless, the IPCC claims that one of the least known aspects of climate research is the microphysical characteristics of clouds.
“Moreover, the evaporation of droplets is an important process, not only in the context of atmospheric clouds, but also within the field of infectious medicine. Tiny droplets that are produced when we sneeze can contain virus particles. If these droplets evaporate, the virus particles can remain in the air and infect others,” Mehlig stated.
In addition, Professor Mehlig is a coauthor of another study that explains the motion of solid particles inside clouds, including ice crystals.
Mehlig concluded, “The ice crystals and the water droplets affect each other. But we don’t yet know how.”
Journal References:
Fries, J., et. al. (2024) Lagrangian Supersaturation Fluctuations at the Cloud Edge. Physical Review Letters. doi:10.1103/PhysRevLett.131.254201
Bhowmick, T., et. al. (2024) Inertia Induces Strong Orientation Fluctuations of Nonspherical Atmospheric Particles. Physical Review Letters. doi:10.1103/PhysRevLett.132.034101.