The effect on thunderstorm charging of the rate of rime accretion by graupel

Electrification and lightning are simulated for a small continental multicell storm. The results are consistent with observations and thus provide additional understanding of the charging processes and evolution of this storm. The first six observed lightning flashes, all negative cloud-to-ground (CG) flashes, indicated at least an inverted dipole charge structure (negative charge above positive). Negative CG flashes should be energetically favorable only when the negative charge region contains appreciably more charge than the lower positive region. The simulations support the hypothesis that the negative charge is enhanced by noninductive charge separation higher in the storm that also causes development of an upper positive charge region, resulting in a "bottom-heavy" tripole charge structure. The two-moment microphysics scheme used for this study can predict mass mixing ratio and number concentration of cloud droplets, rain, ice crystals, snow, graupel, and hail. (Hail was not needed for the present study.) Essential details of the scheme are presented. Bulk particle density of graupel and hail can also be predicted, which increases diversity in fall speeds. The prediction of hydrometeor number concentration is critical for effective charge separation at higher temperatures (−5 < T < −15) in the mixed-phase region, where ice crystals are produced by rime fracturing (Hallett-Mossop process) and by splintering of freezing drops.

show abstract

“…A hybrid scheme ( Fig. 1) was developed that merged the parameterization of Brooks et al (1997) for temperature T > −15…”

Section: Model Detailsmentioning

confidence: 99%

Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

Mansell

Ziegler

Bruning

2010

Journal of the Atmospheric Sciences

418

312

View full text Add to dashboard Cite

show abstract

“…Since the non-inductive charge separated during collisions between ice-phase particles generally depends on temperature, the relative velocity of the collisions, hydrometeor concentration and the supercooled droplet size spectrum (Takahashi 1978;Jayaratne et al 1983;Gardiner et al 1985;Saunders et al 1991;Brooks et al 1997;Saunders and Peck 1998), the contributions of the non-inductive charging process to electrification in these four cases are the same. The time evolution of the non-inductive charging rate is presented in Fig.…”

Section: Charging Ratementioning

confidence: 99%

Effects of the Inductive Charging on the Electrification and Lightning Discharges in Thunderstorms

Shi¹,

Tang²,

Tan³

2016

Terr. Atmos. Ocean. Sci.

View full text Add to dashboard Cite

A two-dimensional cloud model with electrification and lightning processes is used to investigate the role of inductive charge separation in thunderstorm clouds. For the same dynamic and microphysical evolution, four cases that the same noninductive charging parameterization is combined with different inductive charging process are compared. Non-inductive charge separation alone is found to be sufficient to produce a dipolar charge structure. Intracloud (IC) and positive cloud-toground (+CG) flashes are initiated between a main negative charge region and an upper positive charge region. The inductive charging process between graupel and cloud droplets exhibits a normal tripole charge structure, consisting of a lower positive charge region under the main negative charge region. In the simulated tripole structure, negative cloud-to-ground (-CG) flashes are initiated between the main negative and lower positive charge regions. In addition, inductive charge separation between the graupel and ice crystal is found to be capable of producing strong charge separation in a dipole charge structure. Tests with inductive graupel-ice crystals process produce more flashes than that in the other cases.

show abstract

“…Graupel particles are the initial ice crystals forming as the moist air reaches a height where the temperature is below zero. According to literature [34], [35], [37], [38], [39], [41], [42], [43] the induction has a less important influence in the early stages of cloud electrification. However, in later stages of cloud electrification, the importance of the induction grows until it becomes of secondary importance, mostly when the field of the cloud exceeds the strength of the "fair weather" field.…”

Section: Lightning Formation As Results Of Inductive Charging Inductimentioning

confidence: 99%

“…According to measurements in the last few years [32], [41], [42], the characteristic of aerosol particles presents the peculiarity of accumulating positive electric charge. This charge is the result of incident energetic radiation assisting the release of free electrons from the outermost layer of solid surfaces or particles.…”

Section: Lightning Formation As Results Of Inductive Charging Photoelmentioning

confidence: 99%

“…This warms up the cold air, and the dust rises to reach the ionosphere, producing more ions with the help of the galactic cosmic rays. The result of all this is large and electrically violent thunderstorms in the littoral areas [32], [42], [45]. Another theory developed by viewing the islands as a miniaturized representation of continents came from Williams et al in 2005 [55].…”

Section: Formation Of Charge Layersmentioning

confidence: 99%

See 1 more Smart Citation

Protection of electronics in composite structures against indirect lightning

Blaj¹

View full text Add to dashboard Cite

SummaryDamage resulting from an interaction with lightning current in a military naval vessel, especially in a conflict zone and at the time of a conflict, which leads to the incapacitation of vital activities on the ship, is unacceptable. Because many potential conflict zones are in littoral areas, and because of the increase in lightning activity, both now and expected in the years to come, the provision of protection for naval vessels sailing in those waters should be a high priority. The fact that many standards exclude both naval vessels and the littoral area transforms this work into a potential contemporary solution.With the knowledge about the formation of charge layers in the atmosphere, and about the influence such weather phenomena as fog, clouds, and aerosols have on the transport of additional charge particles, it is possible to understand the formation of lightning. A review of the existing thunderstorm prediction models, and finding a way to verify and update the accuracy of such, is equally important at this stage. Merely understanding the root cause of the problem will not be enough to solve the problem, and therefore an extensive evaluation of the available literature, with a special attention to standards, also has to take place. Evaluating risks and finding what was previously accomplished by others, and any stones they have left unturned, can improve the life expectancy of a system or building block when applying and improving the existing technology. Conventional lightning protection measures serve as points of departure to reach the goals of this research. Such issues as positioning, zoning, and proximity to other components more attractive to lightning strikes must not be overlooked since these are equally important. The rolling sphere concept, as described in civil standards, is applied to naval vessels, and serves now as a basic tool within THALES to estimate the risk of lightning, and possible damage and/or interference. Steps taken by other branches of industry in this direction is investigated too. Investigation and a thorough analysis of other protective methods will help to generate the right ideas to tackle the issue and to improve lightning protection of electronics enclosed by composite structures against both direct contact with the lightning current, and the indirect effects of the associated electric and magnetic fields. Diverters are used by the aircraft industry and the possible use to protect radars under a composite non-conducting radome has been investigated experimentally. The constant increase in our dependency on composite panels throughout many branches of industry, including the naval and maritime sectors, make it necessary to quantify and measure all the risks associated with lightning strikes. Evaluating risks, and where necessary fixing them, will guarantee the successful use of this technology. The lack of shielding properties, and the high likelihood of deterioration and damage as a result of a lightning attachment, mean improvements are essential to make the u...

show abstract

The effect on thunderstorm charging of the rate of rime accretion by graupel

Cited by 93 publications

References 28 publications

Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

Simulated Electrification of a Small Thunderstorm with Two-Moment Bulk Microphysics

Effects of the Inductive Charging on the Electrification and Lightning Discharges in Thunderstorms

Protection of electronics in composite structures against indirect lightning

Contact Info

Product

Resources

About