A Ground-Lightning Environment for Engineering Usage
Abstract
Data on lightning incidence are first examined. Expressions are derived relating lightning incidence to the monthly thunderstorm-day statistic, to diurnal variation of activity, and to structure height. By using these expressions the number of lightning strikes to be expected over any period of time can be estimated, on a climatological basis, for a structure of known height located anywhere in the world. The following physical parameters of lightning are then discussed: peak current, time to peak current, rate of current rise, magnitude and duration of continuing currents, total charge transfer, number of strokes, and time between strokes. Median values and statistical distributions for the parameters are deduced; the statistics can usually be conveniently expressed in terms of a log-normal law. Several models for lightning are derived and expressed in convenient analytical forms. Two types of models are identified--basic models developed solely from the physical properties of lightning, and applied models modified appropriately for use with equipment, the lightning sensitivity of which is partially defined. While the main emphasis of the report is on the direct effects of flashes to ground, discussions are also given of the physical characteristics of intracloud discharges, and of the static and electromagnetic fields generated by lightning.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1972
- Accession Number
- AD0907891
Entities
People
- Edward T. Pierce
- Nicholas Cianos
Organizations
- SRI International