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Full-Text Articles in Physical Sciences and Mathematics
Evolution Of Cloud-To-Ground Lightning Discharges In Tornadic Thunderstorms, Wendy L. Seaman
Evolution Of Cloud-To-Ground Lightning Discharges In Tornadic Thunderstorms, Wendy L. Seaman
Theses and Dissertations
Air Force operations are directly impacted by weather on a daily basis. Erroneous forecasts negatively impact mission readiness and consequently cost the government time, in terms of wasted man-hours, and money. Advanced forecast lead-time could make a difference to minimize loss to both USAF personnel and assets. This study examined lightning data from 64 storm events from 1995-2000 in search of unique lightning signatures indicative of tornadic activity. Overall flash rates, percentage of positive flashes, positive and negative peak currents and multiplicity for each case were separated into two categories based on tornado intensity and season of occurrence. Based on …
Analysis Of Cloud-To-Ground Lightning Clusters With Radar Composite Imagery, Rhonda B. Scott
Analysis Of Cloud-To-Ground Lightning Clusters With Radar Composite Imagery, Rhonda B. Scott
Theses and Dissertations
The most recent research conducted at the Air Force Institute of Technology involved studying a large volume of lightning data without coupling radar imagery (Parsons 2000). Parsons finding could not be acted on because no individual storms were studied. The primary goal of this research is to determine whether the techniques used by Parsons can be applied to storms by examining the radar imagery and lightning data. This research used the methodology applied to lightning data by Parsons and radar imagery to determine whether the location of lightning clusters were located near storms. A composite reflectivity radar image was generated …
Development Of Predictors For Cloud-To-Ground Lightning Activity Using Atmospheric Stability Indices, Kenneth C. Venzke
Development Of Predictors For Cloud-To-Ground Lightning Activity Using Atmospheric Stability Indices, Kenneth C. Venzke
Theses and Dissertations
A detailed examination was performed on several commonly applied atmospheric stability indices and lightning activity from 1993 to 2000 to determine the indices usefulness as predictive tools for determining cloud-to-ground lightning activity. Predetermined radii of 50 nautical miles around upper-air stations in the Midwest U.S. were used for the lightning summaries. Also explored is an improvement upon the commonly accepted thresholds of the stability indices as general thunderstorm indicators. An improvement was found and new threshold ranges were developed for relating stability index values to lightning occurrence. Traditional statistical regression methods failed to find a significant predictive relationship. By examining …
Atmospheric Conditions Associated With Lightning During Snow And Ice Events, Randall J. Haeberle
Atmospheric Conditions Associated With Lightning During Snow And Ice Events, Randall J. Haeberle
Theses and Dissertations
The purpose of this research was to find the atmospheric mechanisms associated with lightning in snow and ice events. The specific mechanisms that were examined were low-level wind shear, upper level divergence, surface temperature, low-level temperature, the -10 ° C level, and precipitable water. A chi-squared dependency test showed the strong association of low-level wind shear to each precipitation type (snow, sleet/freezing rain, rain) in two separate studies. Surface temperature appeared to have a relationship to lightning in all precipitation categories, while no significant relationship to lightning in all precipitation categories, while no significant relationship was found with upper level …