Laboratory Modelling of Cumulus Behavior in a Gaseous Medium

Eden, H. F.; Vonnegut, B.

doi:10.1175/1520-0450(1965)004<0745:lmocbi>2.0.co;2

Cited by 11 publications

(6 citation statements)

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“…His evidence has therefore been considered questionable. Eden and Vonnegut [1965] investigated laboratory clouds and found that screening layers quickly formed on the top layers of their artificially electrified water aerosols. Vonnegut et al [1966] and others inferred the existence of charged screening layers around thunderclouds by external potential gradient measurements with an instrument on a U2 aircraft, but they were not able to determine much about the nature of the layers.…”

Section: Concludi -Ng Remarksmentioning

confidence: 99%

Thunderstorm on July 16, 1975, over Langmuir laboratory: A case study

Winn¹,

Moore²,

Holmes³

et al. 1978

J. Geophys. Res.

104

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The electric field along the path of an instrumented balloon was closely coupled to the wind profile and to the radar echo structure of a weak thunderstorm over Langmuir Laboratory on July 16, 1975. The balloon ascended at 3.5 m/s into the southern part of the storm, where a stable layer had stopped the cloud's vertical convection at 6.4 km above sea level. At lower altitudes, near the cloud base, the balloon rose past two nearby oppositely charged regions which were associated with a precipitation echo and with an outflow of air from the storm. When the balloon ascended into clear air through the top of the lower cloud at 6.4‐km altitude, its motion indicated a sharp change in wind direction, and its electric field meter showed an abrupt decrease in field intensity, probably from a screening layer at the cloud boundary. Above 7.5 km the balloon encountered a slanted and charged downdraft just before entering the northern part of the storm under its anvil cloud. This downdraft, which had a velocity of about 6 m/s, was a prominent and persistent feature of the cloud's circulation. It held the balloon at a nearly constant altitude of 7.7 km for 10 min while carrying it 3 km toward the center of the storm. When the electric field meter descended, after release from the balloon, it encountered the downdraft a second time, 24 min after its first encounter. Electric field measurements suggest that the downdraft was carrying a negative charge. Our measurements on this storm also contain evidence for vertical transport of horizontal momentum and for a net positive charge in the upper part of the storm.

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Section: Concludi -Ng Remarksmentioning

confidence: 99%

Thunderstorm on July 16, 1975, over Langmuir laboratory: A case study

Winn¹,

Moore²,

Holmes³

et al. 1978

J. Geophys. Res.

104

View full text Add to dashboard Cite

show abstract

“…Such patterns may be thermally driven, but it is also possible that instabilities in the planetary boundary layer resulting from horizontal shear might be involved (see below). Eden and Vonnegut (1965) have reported an interesting analogy to the behavior of electrical sheathing layers above large thunderstorms. Disturbances were observed in a sheathing layer over a dense cloud of water droplets formed from dry ice in a box after a convective penetration of the top of the cloud.…”

Section: Fig 5 Smoke Traces Of Flow Of Stably Stratified Air Over Amentioning

confidence: 96%

adventures in atmospheric simulation

Hidy

1967

Bulletin of the American Meteorological Society

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Laboratory investigations of processes related to atmospheric behavior have long been a resource of fundamental knowledge to workers in meteorology. In fact the history of progress in laboratory simulation closely follows the development of a wide spectrum of key ideas and hypotheses about the atmospheric processes on scales ranging from molecular activity to planetary circulation. This paper presents a very brief survey of the exciting wealth of information evolving from an ever increasing variety of laboratory experiments devoted to atmospheric phenomena.

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“…This results in more ion depletion close to the cloud surface than would occur with the ing layer is a charge concentrating mechanism and it produces the highest concentrations of space charge that have yet been identified in thunderstorms. Speculations on the role of these charge accumulations have been put forth by a number of investigators [Grenet, 1947;Vonnegut, 1955Vonnegut, , 1963Gunn, 1956;Wilson, 1956;Eden and Vonnegut, 1965;Phillips, 1967…”

Section: Screening Layer Solutio]n'mentioning

confidence: 99%

Electrical screening layers around charged clouds

Brown¹,

Krehbiel²,

Moore³

et al. 1971

J. Geophys. Res.

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Grenet and Vonnegut have shown that an electrified cloud surrounded by conducting clear air acquires an electrical screening layer around its outer boundaries by droplet capture of ions. The process has been modeled for conditions in which diffusion is assumed to be negligible. Numerical solutions have been obtained for the charge accumulations, for the distribution of the electric field, and for the forces acting on cloud droplets in terms of the length l0 of the ionic mean free path in the cloud. The maximum charge concentration is found to be about 0.5417 ∈0E0/l0 with 63% of the maximum being acquired in a time of ∈0/2 λ± where λ± is the appropriate polar conductivity and ∈0 the effective permittivity of the clear air. The layer's effective thickness for the first 63.2% of the charge is 1.34 l0 and 2.41 l0 for the first 86.5% of the charge. The computed maximum electric force per unit volume is 0.21 ∈0E02/l0 with a maximum divergence of 0.29 ∈0E02/l02 above a maximum convergence of 0.099 ∈0E02/l02. The time constant for a Naperian e‐fold increase in cloud droplet concentration by electrostatic convergence in Stokes law flow is estimated as about 20 μl0/(ā∈0E02) where μ is the molecular viscosity of the air and ā is the average droplet radius.

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Laboratory Modelling of Cumulus Behavior in a Gaseous Medium

Cited by 11 publications

References 0 publications

Thunderstorm on July 16, 1975, over Langmuir laboratory: A case study

Thunderstorm on July 16, 1975, over Langmuir laboratory: A case study

adventures in atmospheric simulation

Electrical screening layers around charged clouds

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