Accession Number : ADA300032

Title :   A Study of the Cloud-To-Ground Lightning Characteristics during the 21-23 November 1992 Widespread Severe Weather Outbreak.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH

Personal Author(s) : Carle, William J.

PDF Url : ADA300032

Report Date : 10 SEP 1995

Pagination or Media Count : 123

Abstract : A synoptic low pressure system developed in Texas on 21 November 1992 and propagated to the Great Lakes region on 23 November 1992. Over 90 tornadoes were spawned throughout the Southeast and parts of the Ohio River Valley. The cloud-to-ground (CG) lightning characteristics for the system were studied in a storm relative coordinate system. Results indicate that a moderate negative correlation exists between the poSitive flash rate and the median first stroke peak current. A higher order correlation exists between the negative flash rate and the mean multiplicity. Maxima of the positive flash density were almost always displaced to the north or east of the maxima in the negative flash density. The effects of shear on bipolar lightning patterns indicate that 13 of the 18 bipolar patterns are most closely oriented with the shear vector associated with the 700 mb-surface layer. A correlation between the magnitude of the shear vector and the length of the bipolar pattern was not found. No correlation was found between the percentage of positive lightning and 31 cases of hail greater than or equal to 0.75 inches. Many of the hail cases were predominantly associated with negative lightning. The lightning characteristics of 21 F3 and F4 tornadoes studied indicate a possible lag time between the peak in the total, positive, and negative CG flash rates of approximately 10 minutes. Large boxed areas were not the most suitable means of associating CG lightning with the tornadic storms due to varying amounts of contamination of the CG flash rate.

Descriptors :   *CLOUDS, *LIGHTNING, *STORMS, DENSITY, WEATHER, LITERATURE SURVEYS, THESES, CHARGED PARTICLES, ICE FORMATION, METEOROLOGICAL SATELLITES, PEAK POWER, INFRARED IMAGES, AIR TO SURFACE, HAIL, ELECTRIC CURRENT, POLARITY, GEOSTROPHIC WIND, ADVECTION, VALLEYS, OHIO RIVER, THUNDERSTORMS, GREAT LAKES, FLASHES, TIME LAG THEORY, FRONTS(METEOROLOGY), TORNADOES.

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE