Caroline Muller looks at clouds differently than most people. Where others may see puffy marshmallows, wispy cotton candy or thunderous gray objects storming overhead, Muller sees fluids flowing through the sky. She visualizes how air rises and falls, warms and cools, and spirals and swirls to form clouds and create storms.
But the urgency with which Muller, a climate scientist at the Institute of Science and Technology Austria in Klosterneuburg, considers such atmospheric puzzles has surged in recent years. As our planet swelters with global warming, storms are becoming more intense, sometimes dumping two or even three times more rain than expected. Such was the case in Bahía Blanca, Argentina, in March 2025: Almost half the city’s yearly average rainfall fell in less than 12 hours, causing deadly floods.
Atmospheric scientists have long used computer simulations to track how the dynamics of air and moisture might produce varieties of storms. But existing models hadn’t fully explained the emergence of these fiercer storms. A roughly 200-year-old theory describes how warmer air holds more moisture than cooler air: an extra 7 percent for every degree Celsius of warming. But in models and weather observations, climate scientists have seen rainfall events far exceeding this expected increase. And those storms can lead to severe flooding when heavy rain falls on already saturated soils or follows humid heatwaves.
Clouds, and the way that they cluster, could help explain what’s going on.
A growing body of research, set in motion by Muller over a decade ago, is revealing several small-scale processes that climate models had previously overlooked. These processes influence how clouds form, congregate, and persist in ways that may amplify heavy downpours and fuel larger, long-lasting storms. Clouds have an “internal life,” Muller says, “that can strengthen them or may help them stay alive longer.”
Other scientists need more convincing, because the computer simulations researchers use to study clouds reduce planet Earth to its simplest and smoothest form, retaining its essential physics but otherwise barely resembling the real world.