When clouds flock together – Ars Technica
Some models suggest that clouds (and the convection that generates them) will cluster more together with global warming – and produce more extreme precipitation that will often far exceed what theory predicts. But other simulations suggest the clouds will gather less. “It seems like there’s still a range of answers,” says Allison Wing, a climate scientist at Florida State University in Tallahassee who has compared different models.
Scientists are beginning to try to reconcile some of these inconsistencies using powerful types of computer simulations called global storm-resolving models. These can capture the fine structures of clouds, thunderstorms and cyclones while simulating the global climate. They provide 50 times greater realism than global climate models generally used by scientists, but require 30,000 times more computing power.
Using one such model in a paper published in 2024, Bao, Muller and their collaborators found that clouds in the tropics gathered more together as temperatures rose, leading to less frequent but larger storms, lasting longer and, over the course of a day, dumping more rain than theory predicted.
But that work relied on a single model and simulated conditions from a near future date: the year 2070. Scientists need to run longer simulations using more storm-resolving models, Bao says, but very few research teams can afford to run them. They require so much computing resources that they are typically run in large centralized centers, and scientists occasionally hold “hackathons” to analyze and share data.
Researchers also need more real-world observations to understand some of the biggest unknowns about clouds. Although many recent studies using satellite data have linked cloud accumulation to heavier precipitation in the tropics, there are significant data gaps in many tropical regions. This weakens climate projections and leaves many countries ill-prepared. In June 2025, floods and landslides in Venezuela and Colombia swept away buildings and killed at least a dozen people, but scientists don’t know what factors made those storms worse because data is so meager. “No one really knows yet what triggered this,” says Hernández Deckers.
New granular data is on the way. Wing is analyzing precipitation measurements from a German research vessel that crossed the tropical Atlantic Ocean for six weeks in 2024. The ship’s radar mapped convective clusters associated with the storms it passed through. The work should therefore help researchers see how clouds are organized over large areas of the ocean.
And an even more global vision is on the horizon. The European Space Agency plans to launch two satellites in 2029 that will measure, among other things, the near-surface winds that churn the Earth’s oceans and brush against mountain peaks. Perhaps, scientists hope, the data sent back by these satellites will finally provide a better understanding of cloud clusters and the heaviest rain that falls from them.
The research and interviews for this article were partly funded by a journalism residency funded by the Institute of Science and Technology Austria (ISTA). The ISTA had no contribution to history. This story was originally published on Knowable Magazine.
