نتایج جستجو برای: lightning
تعداد نتایج: 6387 فیلتر نتایج به سال:
Aircraft are struck by lightning in flight with some regularity and are required to have demonstrated protection against this threat; much of this demonstration is provided by simulating in test the effects of lightning on aircraft structures, components and systems. Clearly these tests need to be carried out in a representative manner and guidance on how to do this is provided in the Aerospace...
-Lightning protection air terminals are placed on structures and other grounded objects with the purpose of capturing the lightning stroke. A well estimation of the lateral protection distance is crucial in predicting the protection area of the lightning rod. This paper focus on a 3-D numerical modelling of lightning attachment based on physical phenomena leading to the formation and the develo...
[1] We consider the use of lumped voltage and current sources in engineering lightning return stroke models with emphasis on those including a tall strike object. If the model is to be used for computing remote electric and magnetic fields, we suggest a representation of the lightning channel as a transmission line energized by a lumped voltage source, with the voltage magnitude being expressed...
[1] The accepted mechanism for whistler generation implicitly assumes that the causative lightning stroke occurs within reasonable proximity to the conjugate foot point of the guiding magnetic field line and that nighttime whistlers are prevalent because of low transionospheric attenuation. However, these assumptions are not necessarily valid. In this study we consider whistler observations fro...
Thirty-nine thunderstorms are examined using multiple-Doppler, polarimetric and total lightning observations to understand the role of mixed phase kinematics and microphysics in the development of lightning jumps. This sample size is larger than those of previous studies on this topic. The principal result of this study is that lightning jumps are a result of mixed phase updraft intensification...
An experimental Very Low Frequency (VLF) World-Wide Lightning Location Network (WWLLN) has been developed through collaborations with research institutions across the world, providing global real-time locations of lightning discharges. As of April 2006, the network included 25 stations providing coverage for much of the Earth. In this paper we examine the detection efficiency of the WWLLN by co...
Lightning flash activities on the central Tibetan Plateau have been studied by using the Lightning Imaging Sensor (LIS) database from 1998 to 2002. The lightning activity shows a clear diurnal variation on the central Plateau. The lightning discharge is weaker on the Plateau than in other low-altitude continental regions because of the lower convective available poential energy (CAPE) on the Pl...
Accurate estimates of tree mortality are essential for the development of mechanistic forest dynamics models, and for estimating carbon storage and cycling. However, identifying agents of tree mortality is difficult and imprecise. Although lightning kills thousands of trees each year and is an important agent of mortality in some forests, the frequency and distribution of lightning-caused tree ...
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...
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...
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