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Exploration of the meteorological characteristics leading to the rapid cessation of cloud-to-ground lightning in winter cyclones along the East Coast of the United States
Abstract
Intense winter East Coast cyclones are capable of producing large amounts of cloud-to-ground (CG) lightning. Few studies have thoroughly investigated winter lightning in the eastern United States. A phenomena common to most of these storms is a rapid cessation of CG lightning over land, north of North Carolina. The primary focus of this study was investigating the possible causes of this rapid cessation. A secondary objective was to explore the characteristics of the CG lightning produced by these storms. Seven intense East Coast cyclones from 1990 to 1996 were analyzed. Soundings, lower atmospheric temperature structure and accumulated precipitation were used to examine possible causes for this rapid cessation. Soundings also provided the vertical wind shear and temperatures used for linear regression analysis of the percentage of positive CG flashes. Further exploration of CG lightning characteristics included peak currents and flash densities. The major cause of the CG lightning cessation appears to be related to stability and not a suppression of charging due to cold lower atmospheric temperatures. The warm sector of all but one storm passed out into the Atlantic Ocean before making it north of North Carolina. This eliminated most of the surface instability for convection. Meanwhile, most soundings from Virginia on northward showed that conditions aloft were too stable to support elevated convection. Colder lower atmospheric temperatures were just representative of stable conditions that would not support convection. Unfortunately, heavy precipitation was not a good indicator of the CG lightning activity during these seven storms. Contrary to previous studies of winter thunderstorms, vertical wind shear of the horizontal wind was not a good predictor of the percentage of positive CG flashes. A combination of temperature and vertical wind shear data yielded better results. Finally, maximum peak current values showed a preference for the main CG lightning region south of Virginia. This study shed light on some of the aspens of winter CG lightning during intense East Coast cyclones. However, many more studies are needed within this field.
Description
Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 185-188).
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Citation
Demetriades, Nicholas William Snow (1999). Exploration of the meteorological characteristics leading to the rapid cessation of cloud-to-ground lightning in winter cyclones along the East Coast of the United States. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1999 -THESIS -D455.
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