# Brookhaven data: marine stratocumulus drizzle more often than cumulus at equal liquid water path

- Published: 2026-11-05 03:23 UTC
- Section: Planet › Climate
- Tags: warm rain formation, marine stratocumulus, oceanic cumulus, liquid water path, collision-coalescence, precipitation below cloud base, Doppler radar clouds, Katia Lamer, Brookhaven National Laboratory, weather model parameterization
- URL: https://realtech.media/news/rt-2c8d3327cbad6badc4d18f24_brookhaven_data_marine/

**Multi-year measurements in four ocean regions show that precipitation below cloud base depends on cloud type, not only on liquid water content.**

![Brookhaven data: marine stratocumulus drizzle more often than cumulus at equal liquid water path](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/fd6f651b4da348e3.webp)
*scinexx*

Researchers at Brookhaven National Laboratory led by Katia Lamer analysed more than 700,000 cloud samples from multi-year observations in four ocean regions. The work was published in Proceedings of the National Academy of Sciences [1]. The sites were the Azores, Barbados, Gan island in the Indian Ocean and a ship route between Los Angeles and Hawaii. The authors reassessed the properties of precipitation just beneath cloud base [1].

## Measurements and stratocumulus results

Lidar was used to determine cloud boundaries. Doppler radars recorded the number and size of precipitation drops and the air motion, and microwave radiometers gave the liquid water path (LWP). This made it possible to compare clouds with similar amounts of water.

According to the authors, warm-rain characteristics are consistent within a cloud regime but differ substantially between stratocumulus and cumulus [1]. Under marine stratocumulus, precipitation was observed in over 56% of cloudy columns with LWP below 130 g m⁻², and in more than 84% of columns with LWP above 130 g m⁻² [1]. The measurements were made just below the clouds, so they do not necessarily show rain that reaches the sea surface.

## Cumulus and drop growth histories

At the same LWP, oceanic cumulus precipitated less often than stratocumulus. On average their drops were two times larger and one to two orders of magnitude fewer [1]. Cumulus updrafts were about two times stronger and adiabaticity was lower than in stratocumulus. The authors note that both factors can affect how drops grow [1].

For stratocumulus with low LWP, the precipitation characteristics are generally consistent with growth by collision–coalescence during gravitational free fall. For cumulus, they cannot be explained without additional processes [1]. The authors suggest that warm-precipitation parameterizations in models should more explicitly account for small-scale dynamical processes, and that Lagrangian particle-tracking approaches deserve further study in models and observations [1].

Lamer said the results call for checking model parameters that artificially suppress rain formation in marine stratocumulus. She also said the findings encourage approaches that follow individual drops through a cloud. The results rest on long-term observations rather than direct tracking of drop trajectories. Whether the proposed paths and evaporation cause the differences remains to be shown by further measurements and more detailed models.

## Sources

1. [Proceedings of the National Academy of Sciences](https://doi.org/10.1073/pnas.2608656123)
2. [scinexx](https://www.scinexx.de/news/geowissen/luftbewegungen-in-wolken-koennten-die-regenbildung-ueber-dem-meer-beeinflussen)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-2c8d3327cbad6badc4d18f24_brookhaven_data_marine/