نتایج جستجو برای: they produce lightning

تعداد نتایج: 1269572  

2003
N. L. Aleksandrov

This paper considers three interconnected problems: (i) initiation of a downward lightning in a thundercloud and that of an upward lightning near tall grounded structures; (ii) conditions for lightning development in the cloud-to-ground gap and the effects of lightning trajectory and branching on discharge parameters; and (iii) physical mechanism of the lightning return stroke and peculiarities...

Journal: :فیزیک زمین و فضا 0
مریم قرایلو استادیار، گروه فیزیک فضا، مؤسسۀ ژئوفیزیک دانشگاه تهران، ایران سمانه ثابت قدم استادیار، گروه فیزیک فضا، مؤسسۀ ژئوفیزیک دانشگاه تهران، ایران سرمد قادر دانشیار، گروه فیزیک فضا، مؤسسۀ ژئوفیزیک دانشگاه تهران، ایران

lightning is a characteristic of severe weather and often associated with hail and heavy rainfall. it is a natural hazard with potential threat to human life and considerable damages to aviation structures. therefore, lightning prediction is critical and the real-time lightning detection systems are able to determine the location of cloud-to-ground (cg) lightning strikes accurately.generally ma...

2005
Thomas L. Murray Richard P. Hoblitt Christina A. Neal

The Alaska Volcano Observatory's lightning detection system detected and located 171 lightning strokes during the August 18, 1992, eruption of the Crater Peak vent of Mount Spurr volcano in Alaska. The strokes, predominantly intracloud, were detected during a 70-minute interval that began more than an hour into the eruption. All detected strokes were of positive polarity. The spatial distributi...

2014
Swati Sharma Shoba Krishnan Ajay Khandare

Lightning discharge emits RF energy over a wide range of frequencies. During cloud to ground lightning, when high currents occur in previously ionized channels, the most powerful emissions occur in the Very Low Frequency range. VLF (very low frequency) refers to radio frequencies spectrum range of 3 kHz to 30 kHz. Detection of lightning makes it possible to avoid various harmful effects occurri...

Journal: :Journal of forensic and legal medicine 2007
O P Murty

This is a case report of an environmental accident due to lightning where one school boy sustained current, blast, and flame effects of it. A bolt of lightning directly struck the pole of a football ground and the scatter struck the child. In addition to burn injuries, he showed an exit wound of lightning in left foot. The exit wound of lightning current is a very rare finding. The body of vict...

2009
Victor P. Pasko

[1] It has been pointed by C. T. R. Wilson in 1920 that sudden reduction of the electric field inside a thundercloud immediately following a lightning discharge should produce an infrasound signature. In the present work, a model based on linearized equations of acoustics with classical viscosity and atmospheric gravitational stratification effects is employed to study electrostatic production ...

2004
J. R. Dwyer H. K. Rassoul M. Al-Dayeh L. Caraway A. Chrest M. A. Uman V. A. Rakov K. J. Rambo D. M. Jordan J. Jerauld C. Smyth

[1] We report measurements of the x-ray emission from rocket-triggered lightning, made during the summer of 2003, using four instruments placed between 15 and 40 m from the lightning channels. X-rays were measured 0–80 ms just prior to and at the beginning of 73% of the 26 return strokes observed. The emission was composed of multiple, very brief bursts of x-rays in the 30–250 keV range, with e...

Journal: :Academic emergency medicine : official journal of the Society for Academic Emergency Medicine 2002
Mary Ann Cooper

The four classic electrical mechanisms of lightning injury cannot account for all injuries. A fifth mechanism, injury by a weak upward streamer that does not become part of a completed lightning channel, has long been postulated in the engineering literature by lightning researchers. This paper reports a case of death where injury from a weak upward streamer is strongly suspected following fore...

2005
DANIEL J. CECIL STEVEN J. GOODMAN DENNIS J. BOCCIPPIO EDWARD J. ZIPSER STEPHEN W. NESBITT

During its first three years, the Tropical Rainfall Measuring Mission (TRMM) satellite observed nearly six million precipitation features. The population of precipitation features is sorted by lightning flash rate, minimum brightness temperature, maximum radar reflectivity, areal extent, and volumetric rainfall. For each of these characteristics, essentially describing the convective intensity ...

2004
Marcos André da Frota

A lightning stepped leader model is developed. To predict the stepped leader is important to protect installations at ground against lightning. The numerical technique TLM (Transmission-line matrix) is applied.

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