Mathematical Geophysics Research Spotlight

Can Patches of Cold Air Cause Thunderstorms to Cluster?

Small-scale collisions between pools of cold air may play an important role in organizing hurricanes and other crucial atmospheric phenomena, according to newly developed conceptual models.

Source: Geophysical Research Letters


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In portions of Earth’s atmosphere, initially scattered thunderstorm clouds display a spontaneous tendency to cluster. Although this convective self-aggregation is believed to play an important role in the organization of squall lines, hurricanes, and the most important tropical weather cycle, the Madden-Julian Oscillation, the dynamics behind the phenomenon are still poorly understood.

Previous researchers have proposed that self-aggregation is due to differences in heat loss from cloudy regions compared to clear ones, but to date no direct correlation has been found. Now Haerter explores whether convective self-aggregation could instead result from interactions between cold pools, 10- to 100-kilometer-wide pockets of cold air that develop when evaporative cooling occurs beneath precipitating cumulonimbus and other convective clouds.

To further investigate the role of these small-scale interactions, the author developed a series of simple, conceptual models that treat cold pool–driven self-aggregation as a critical phenomenon. The findings indicated that collisions between multiple cold pools can lead to convective self-aggregation but that the triggering of a single cold pool does not.

By bridging the fields of statistical physics and atmospheric science, the author’s research offers novel insights into the potential linkage between small-scale interactions and universal behavior. The results offer a compelling mechanism for explaining how interactions between cold pools, rather than differences in radiation, ultimately organize large-scale, atmospheric phenomena. (Geophysical Research Letters, https://doi.org/10.1029/2018GL081817, 2019)

—Terri Cook, Freelance Writer

Citation: Cook, T. (2019), Can patches of cold air cause thunderstorms to cluster?, Eos, 100, https://doi.org/10.1029/2019EO123641. Published on 15 May 2019.
Text © 2019. The authors. CC BY-NC-ND 3.0
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