Related Experiment Video
Updated: Aug 11, 2026
12:11
Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
Highly localized droplet clustering in shallow cumulus clouds
Birte Thiede1,2, Michael L Larsen3,4, Freja Nordsiek1
1Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen 37077, Germany.
Summary
Water droplet clustering in clouds is stronger and more localized than previously observed. This finding challenges current cloud microphysics models and impacts understanding of precipitation and Earth's climate.
Area of Science:
- Cloud physics
- Atmospheric science
- Earth science
Background:
- Droplet size and clustering in warm clouds are crucial for cloud evolution, radiation, Earth's energy balance, and water cycle.
- Strong droplet clustering is proposed as a mechanism for droplet growth and precipitation in clouds.
- Resolving droplet clustering on sub-centimeter scales is a significant challenge in cloud research.
Purpose of the Study:
- To investigate the spatial distribution and clustering of water droplets in shallow cumulus clouds.
- To challenge existing cloud microphysics frameworks with new observational data.
- To assess the implications of observed droplet clustering for precipitation initiation and cloud modeling.
Main Methods:
- Spatially resolved in-situ holographic measurements were utilized.
- Data was collected using a tethered aerostat for high-resolution observations.
- Measurements focused on shallow cumulus cloud environments.
Main Results:
- Cloud droplet clustering in shallow cumulus clouds was found to be significantly stronger than previously documented.
- Droplet clustering was observed to be highly localized, occurring on sub-centimeter scales.
- Previous aircraft-based observations in stratocumulus clouds indicated weaker, averaged clustering over larger scales.
Conclusions:
- The study demonstrates significantly stronger and more localized droplet clustering in shallow cumulus clouds than previously thought.
- These findings necessitate a re-evaluation of current cloud microphysics frameworks.
- The results have important implications for understanding precipitation processes and improving cloud models in climate research.
Related Concept Videos
01:10Types of Coprecipitation
Coprecipitation is the contamination of a precipitate by otherwise soluble species and occurs via different processes. In colloidal precipitates, coprecipitation occurs via surface adsorption. For instance, barium sulfate has a primary layer of adsorbed barium ions and a secondary layer of nitrate counterions. This results in contamination of the precipitate by barium nitrate.
Sometimes, ions in a crystal lattice can undergo isomorphous replacement by inclusions of similar charge and size. For...
Sometimes, ions in a crystal lattice can undergo isomorphous replacement by inclusions of similar charge and size. For...
01:12Precipitation Processes
The experimental conditions in a gravimetric analysis should be optimized to maximize the particle size and purity of the obtained precipitate. Ideally, the concentration of the precipitating reagent should be low with effective stirring to maintain low relative supersaturation for the growth of large crystals. In homogeneous precipitation, the precipitant is slowly generated by a chemical reaction in the solution to avoid local reagent excesses. For example, urea decomposes gradually to...
01:17Precipitation and Co-precipitation
Precipitation and coprecipitation methods can be used to separate a mixture of ions in a solution. In qualitative inorganic analysis, ions that form sparingly soluble precipitates with the same reagent are separated based on the differences in solubility products. For example, consider the separation of Cu(II) and Fe(II) ions by precipitation as insoluble sulfides. First, copper(II) sulfide is precipitated by the addition of acidic H2S, where the dissociation of H2S is suppressed. Adding H2S...
01:16Precipitate Formation and Particle Size Control
In precipitation gravimetry, the precipitating agent should react specifically or selectively with the analyte. While a specific reagent reacts with the analyte alone, a selective reagent can react with a limited number of chemical species.
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...
01:13Excess Pressure Inside a Drop and a Bubble
The shape of a small drop of liquid can be considered spherical, neglecting the effect of gravity. This drop can further be considered as two equal hemispherical drops put together due to surface tension. The forces acting on the spherical drop are due to the pressure of the liquid inside the drop, the pressure due to air outside the drop, and the force due to the surface tension acting on the two hemispherical drops.
02:39Phase Transitions: Vaporization and Condensation
The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize (convert into vapor). The process is called vaporization—a surface phenomenon. Vaporization occurs when the thermal motion of the molecules overcome the intermolecular forces, and the molecules (at the surface) escape into the gaseous state. When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules...