Öktem, Giangrande, and Romps, Pinned clouds over industrial sources of heat during TRACER, BAMS, 2026
Paper
Description
In 2021, the ARM StereoCam instruments were deployed to Houston, TX as part of the TRACER campaign, where they provided time-lapse photography and 3D reconstructions of the clouds. Hours spent watching these time-lapse videos revealed the frequent existence of pinned cumulus clouds: long-lived convective clouds sitting atop fixed locations. These pinned clouds appear in the early morning before solar heating of the surface triggers more widespread clouds.
Using the stereo reconstructions, we are able to identify the locations of these pinned clouds. Using data from the Texas Commission on Environment Quality, we find that the cloud locations are atop known sources of heat. Furthermore, we are able to quantify the power emitted by the stacks responsible for triggering and pinning these clouds. We find that the clouds appear on mornings that are primed for moist convection; the industrial sources of heat provide the nudge needed to form these clouds before solar heating of the surface takes over.
Due to their statistically steady nature, their triggering by known heat sources, and the ample data collected on the clouds and their environment by the TRACER instruments, these pinned clouds represent a unique opportunity to test theories of moist convection.
An example of two pinned clouds outlined in white sitting atop two main sources of heat from industrial facilities in the greater Houston area.