New cloud model could help climate research

Clouds have several important functions. They act as reflectors whereby water droplets in a cloud reflect radiation back to Earth, contributing to the greenhouse effect. Credit: University of Gothenburg

When clouds meet a clear sky, the cloud droplets evaporate as they mix with dry air. A new study involving researchers from the University of Gothenburg has succeeded in capturing what happens in the model. Ultimately, this could lead to more accurate climate modeling in the future.

Clouds in the sky have a significant effect on our climate. Not only do they produce rain and provide shade from the sun, they also act as large reflectors that block the radiation of heat from the Earth—commonly known as the greenhouse effect.

“Although clouds have been studied for a long time, they are one of the biggest sources of uncertainty. Bernhard Mehlig, professor of complex systems at the University of Gothenburg, explains. “That’s because there are many factors that determine how clouds affect radiation. And turbulence in the atmosphere means that everything is constantly moving. This makes things even more complicated. Gives.”

Focusing on the edge of the cloud

An article in Physical examination letters presents A new statistical model that predicts how the number of water droplets, their size and Chat at the edge of a turbulent cloud. The distribution of water droplets is important because it affects how clouds reflect radiation.

“The model describes how droplets shrink and grow at the edge of a cloud when turbulence mixes with dry air,” says Johann Fries, a former doctoral student in physics and co-author of the study.

The researchers have identified the most important parameters, and built their model accordingly. Briefly, the model takes into account the laws of thermodynamics and the turbulent motion of droplets. The model is in good agreement with previous numerical computer simulations, and explains their results.

Importance of evaporation

“But we are still a long way from the finish line,” continues Professor Mehlig. “Our model is currently able to describe what’s happening in one cubic meter of cloud. Say, fifteen years ago it was only one cubic centimeter, so we’re making progress.”

When policy makers debate. IPCC climate models are highly valued. However, according to the IPCC, the microphysical properties of clouds are among the least understood factors in climate science.

“Furthermore, droplet evaporation is an important process, not only in the context of atmospheric clouds, but also in the field of infectious medicine. Small droplets produced during sneezing can contain virus particles. If this droplets become vapors, May infect others by being airborne.”

Professor Mehlig has also co-authored another study that shows how like ice crystals, move within clouds.

“Ice crystals and influence each other. But we still don’t know how.”

More information:
J. Fries et al, Lagrangian Supersaturation Fluctuations at the Cloud Edge, Physical examination letters (2023). DOI: 10.1103/PhysRevLett.131.254201

Reference: New cloud model could help climate research (2024, February 21) Retrieved February 21, 2024 from https://phys.org/news/2024-02-cloud-climate.html

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