The Effect of a Solar Eclipse on Thermally-Driven Winds in a Small Valley

Winds within a valley typically exhibit a diurnal pattern, with upvalley winds during the day and downvalley winds at night. This pattern is mainly controlled by differential heating and cooling between the valley and adjacent plains. Transition periods occur around sunrise and sunset as these thermally-driven winds reverse direction in the valley. On 21 August 2017, a total solar eclipse took place over the continental United States. In the foothills of the Blue Ridge mountains near Charlottesville, VA, the eclipse was partial and took place in the early afternoon hours, when daytime upvalley winds are typically well-established. The sudden decline in daytime heating provided quasi-laboratory conditions in which to observe the response of valley boundary layer and thermally-driven winds. We designed an observational field campaign to answer the following questions: 1) Is eclipse-induced cooling sufficient to alter valley wind patterns? 2) To what vertical extent do alterations occur? In this poster, we will present results from the field campaign, with a focus on winds that developed before, during, and after the eclipse on 21 August. We show that multiple rotations occurred in the wind direction during and after the eclipse, both at the surface and in the boundary layer. These rotations were different from those occurring during typical morning and evening transitions and depended on the proximity to the valley sidewalls. We present a conceptual model to explain the observations.