GLOBE Eclipse 2024: A Case Study of the Effects of the April 2024 Total Solar Eclipse on Cirrus Clouds and Contrails in the United States of America

Solar eclipses are exciting events, attracting viewers globally. They are also a popular research topic, with scientists considering their effects on insolation, temperature, and even animal behavior. While some eclipse research focuses on how clouds change in the atmosphere, relatively few studies have considered how a solar eclipse may affect high-level clouds, including contrails. High-level clouds, such as cirrus and contrails, have a net warming effect on the Earth. High-level cloud coverage has been increasing, particularly in the midlatitudes, due to an increase in aircraft flights. There are many factors determining if contrails will form, including atmospheric conditions and aircraft engine. There is no shortage of research considering the various factors, but contrail forecasting remains difficult for meteorologists and aviators, perhaps especially during special phenomena that cause rapid atmospheric perturbations such as a solar eclipse. This research takes a unique perspective by coupling model data and satellite imagery with ground observations submitted by volunteers via The Global Learning and Observations to Benefit the Environment (GLOBE) Program during the 8 April 2024 total solar eclipse in six U.S. cities. Volunteer observations give us a clear timeline of the changes occurring before, during, and after the solar eclipse in multiple locations, allowing us to gather more detail than using models or automated ground stations alone. We use models to calculate hourly relative humidity with respect to ice (RHI) throughout the study period and compare contrail potential forecasts, while the volunteer observations tell us how cloud coverage was changing and the type of clouds, including contrails. Volunteers found cirrus and contrails typically increased near the local eclipse maximum (LEM), demonstrating that even temporally short events, like a solar eclipse, may affect atmospheric conditions enough to alter the likelihood of formation of these high-level clouds.