Tropical clouds reach 10% supersaturation, enabling aerosol-driven storm intensification

August 1, 2026 at 05:47 PM1 min

This digest was compiled by AI from multiple sources — links to the originals are below.

Tropical convective clouds can reach water vapor supersaturation levels as high as 10%, according to a study published today in Advances in Atmospheric Sciences. The finding supports the theory that tiny aerosol particles can invigorate storms by accelerating condensation and latent heat release. Earlier aircraft studies likely missed the effect because they sampled clouds that were too shallow or too polluted.

Past Measurement Gaps

Earlier aircraft measurements generally did not detect the high levels of quasi-steady-state supersaturation thought necessary for aerosol convective invigoration. Many campaigns targeted relatively polluted clouds, shallow warm clouds, or sampled below deep convective regions where updrafts are weaker. At greater heights, droplet collisions, precipitation formation, and faster updrafts reduce the total surface area of droplets, allowing supersaturation to build — yet these regions were rarely probed.

The CAMP2Ex Campaign

The new study used aircraft data from NASA’s Cloud, Aerosol and Monsoon Processes Philippines Experiment, conducted in 2019 over the Philippines and adjacent tropical oceans. Researchers from China, the US, and Israel estimated quasi-steady-state supersaturation from measured updraft speeds and cloud droplet size distributions. Supersaturation increased with height, reaching about 10% at approximately −5°C, where the updraft regions consisted mainly of supercooled liquid droplets.

Aerosol Invigoration Mechanism

The extreme supersaturation levels align with conditions required for condensational aerosol convective invigoration. When additional aerosol particles enter such an environment, they can form new droplets, increasing condensation and the release of latent heat. This process can accelerate rising air, potentially intensifying the storm. A companion study published in the same journal offers further support for the mechanism.