High level thunderstorms (sometimes called 'dry thunderstorms') originate from advection of mid level moisture with cloud condensation level near 0°C. Below the moist level lies dry air so that any precipitation particularly, in the form of smaller particles readily evaporates and fails to reach the surface. Charge separation may occur from convection in the moist region, aided by local orographic and local convergence effects, leading to strikes to ground, with the ability to initiate fires under the dry surface conditions. Such events are in contrast to deeper instability thunderstorms, formed in moist air and having cloud base temperatures above 20°C, leading not only to charge generation through the mixed phase regions aloft but giving rise to significant rain at the surface, discouraging any fire starts under the previously dry conditions.
In collaboration with wildfire experts, the Principle Investigator will perform a preliminary investigation into the characteristics of these dry thunderstorms which appear to have a significant influence on the initiation of some wildfires. This investigation will include ascertaining the antecedent conditions that might lead to the formation of electrically active dry thunderstorms.
Broader Impact:
The ultimate purpose of the study is to assemble aspects of the events important for anticipating and forecasting similar future scenarios and to examine the frequency of the particular meteorological and midlevel cloud forming condition and the associated charge generation.
There are further ramifications of the project since the large amount of smoke produced by the fires may lead to health problems extending many miles downwind. The ability to predict such events may have implications for public health as well implications for early deployment of fire fighting capabilities.
