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Physical Sciences and Mathematics Commons™
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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 …
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 …
Analysis Of Cloud-Free Line-Of-Sight Probability Calculations, Joseph J. Golemboski Iii
Analysis Of Cloud-Free Line-Of-Sight Probability Calculations, Joseph J. Golemboski Iii
Theses and Dissertations
Cloud-free line-of-sight probabilities were calculated using two separate methods. The first was a variation of a method developed by the Rand Corporation in 1972. In it, CFLOS probabilities were calculated using empirical data based on five years of photograms taken over Columbia, Missouri and forecasted cloud amounts rather than climatological values. The second was a new approach using the Cloud Scene Simulation Model developed by Phillips Laboratory. Cloud scenes were generated using forecasted cloud fields, meteorological inputs, and thirty random numbers. Water content files were produced and processed through a follow-on program to determine the extinction coefficients at each grid …