Lightning-Warning Systems for Use by Airports (2008) / Chapter Skim
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Appendix B - Glossary of Lightning Terms
Appendix B - Glossary of Lightning Terms
Pages 63-71
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From page 63... ...
63 The text presented in this research study includes a wide range of often unfamiliar words and specialized terminology. For the convenience of the reader, the glossary of lightning terms is presented on the following pages.
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From page 64... ...
Atmospherics -- (Also called atmospheric interference, strays, sferics) The radio frequency electromagnetic radiation originating, principally, in the irregular surges of charge in thunderstorm lightning discharges.
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From page 65... ...
Cloud flash -- (Also called intracloud flash, cloud-to-cloud flash) A lightning discharge occurring between a positively charged region and a negatively charged region, both of which may lie in the same cloud.
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From page 66... ...
Intracloud flash -- A lightning discharge occurring between a positive charge center and a negative charge center, both of which lie in the same cloud; starts most frequently in the region of the strong electric field between the upper positive and lower negative space charge regions. In summer thunderstorms, intracloud flashes precede the occurrence of cloud-to-ground flashes; they also outnumber cloud-to-ground flashes.
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From page 67... ...
Lightning detection network -- An integrated array of lightning direction finders that provide information for trigonometric location of cloud-to-ground lightning discharges. Timing and direction information from individual receivers are combined to provide evolving maps of lightning occurrences across vast regions that sometimes reach beyond the range of storm surveillance radars.
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From page 68... ...
In negative cloud-to-ground flashes the return stroke deposits the positive charge of several coulombs on the preceding negative leader channel, thus charging earth negatively. In positive cloud-toground flashes, the return stroke deposits the negative charge of several tens of coulombs on the preceding positive leader channel, thus increasing positive charge on the ground.
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From page 69... ...
Sferics receiver -- (Also called lightning direction finder.) An instrument that measures, electronically, the direction of arrival, intensity, and rate of occurrence of atmospherics; a type of radio direction finder, it is most commonly used to detect and locate cloud-to-ground lightning discharges from distant thunderstorms.
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From page 70... ...
Stroke density -- The areal density of lightning discharges over a given region during some specified period of time, as number per square mile or per square kilometer. Supply current -- The electrical current in the atmosphere that is required to balance the observed air–earth current of fair-weather regions by transporting positive charge upward or negative charge downward.
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From page 71... ...
Whistler -- A type of VLF electromagnetic signal generated by some lightning discharges. Whistlers propagate along geomagnetic field lines and can travel back and forth several times between the Northern and Southern Hemispheres.
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Key Terms
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