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Researchers at Brookhaven National Laboratory in New York have, for the first time, examined cloud tops in unprecedented detail using a new lidar system, revealing structures at a scale of just one centimeter. The findings show significant differences between the physics of cloud tops and their interior layers, offering new insights into cloud evolution, precipitation formation, and climate impacts, reports Gizmodo.
The team developed a remote-sensing laser lidar capable of capturing cloud structures with roughly one-centimeter spatial resolution—100 to 1,000 times greater than traditional observation tools. The study, published in Proceedings of the National Academy of Sciences, combined lidar measurements with chamber experiments, allowing researchers to distinguish water structures at the cloud top from those deeper inside. These differences, according to the authors, determine how clouds evolve, produce precipitation, and affect Earth's energy balance.
Lead author Fan Yan described the new device as a “microscope for clouds,” detecting and counting individual photons returning from ultra-fast laser pulses. A specialized algorithm converts these signals into highly detailed profiles of cloud structure, providing high-resolution images of cloud dynamics.
To validate the technology, the team used a Wilson cloud chamber in Michigan, where clouds can be artificially created under controlled temperature and humidity. Results showed that existing models misrepresent cloud-top physics: the lidar revealed highly variable droplet distributions at the top, while the interior exhibited a more uniform structure.
These differences arise from two processes—entrainment and sedimentation. Entrainment pulls dry air from above, creating patchy structures, while sedimentation sorts droplets by size. Inside the cloud, strong turbulence quickly mixes droplets into a uniform mass. Near the top, weaker turbulence allows only smaller droplets to remain. Yan explained that many atmospheric models neglect droplet sedimentation or assume all droplets fall at the same speed—a simplification that is valid in turbulent interior regions but fails near cloud tops.
The researchers stress that inaccurate understanding of cloud-top physics can significantly affect climate predictions, including estimates of solar radiation reflection and precipitation formation.
Future plans include using the lidar for direct measurements in the atmosphere. While laboratory chambers cannot fully replicate natural cloud dynamics, the technology represents a major step toward more accurate modeling. This effort complements recent advances in creating the most precise “digital twin” of Earth, which integrates short-term weather data with long-term global processes for improved climate simulations.
