The Role of Ice Specimen Geometry and Impact Velocity in the Reynolds-Brook Theory of Thunderstorm Electrification

Latham, John; Miller, Alfred

doi:10.1175/1520-0469(1965)022<0505:troisg>2.0.co;2

Cited by 27 publications

(11 citation statements)

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“…External potentials from 0 to +-16 kV were applied. Excellent agreement was obtained between theoretical and experimental curves, as well as with Latham and Miller's [ 1965] electrification results (Table 1) 1951, pp. 131-132] and of the target size, provided the latter is much larger than the particles.…”

Section: Splintering and Secondary Crystal Productionsupporting

confidence: 71%

Role of relaxation and contact times in charge separation during collision of precipitation particles with ice targets

Gross¹

1982

J. Geophys. Res.

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The relaxation time of charge transfer and the contact time are two of the parameters controlling charge separation when ice particles collide with one another or with liquid water droplets. For maximum efficiency of charge separation, the relaxation time should be of the same order as the contact time. The relaxation time of charge transport in ice was systematically determined as a function of impurity content and temperature. The contact time for ice/ice collisions was estimated from theory. Depending on the impurity species and their concentration, the relaxation time may be increased or decreased by orders of magnitude with respect to pure ice. Only particles of the order of 10−2 m radius seem to have contact times sufficiently long to give appreciable charge separation by ion transport in collisions between pure or slightly doped (0.1 ppm chloride) ice particles in a dry environment. Charge separation mechanisms involving liquid water and those operating by the transfer of electrons from surface states largely relax these conditions. These results have implications for cloud electrification models involving collision mechanisms.

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Section: Splintering and Secondary Crystal Productionsupporting

confidence: 71%

Role of relaxation and contact times in charge separation during collision of precipitation particles with ice targets

Gross¹

1982

J. Geophys. Res.

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“…Thus, the observed polarity of thunder cloud is established. Latham and Miller [1965] and Latham [1965a] showed that the mechanism of ice particle collisions associated with the development of a temperature gradient across the area of contact is able to electrically charge atmospheric clouds at the required rate of about 2 couI km-' rain -•, thus resolving the long standing discrepancies be- [1966] and Prup-doped ice is smaller than that of pure ice. It pacher [1967a] and calculations by Browning could therefore be expected that the amount and Mason [1963] showed, however, that the of charge generated and separated as a result shattering and splintering mechanism operates of collision between ice crystals and salt-conin clouds only under very restricted conditions.…”

Section: Na -Saltsmentioning

confidence: 99%

“…It is furthermore well established from laboratory experiments [Macklin andRyan 1962, 1965;Pruppacher, 1967b] that, in a supercooled water drop, an ice crystal is growing by multiple branching, thereby producing an interwoven network of dendritic ice structures which are capable of retaining considerable amounts of liquid water. Wind tunnel experiments [List, 1959[List, , 1960Macklin, 1961] and actual observations in clouds (R. R. Braham, personal communication, 1967), have shown that there is a limit to the amount of water that can be frozen onto an ice crystal undergoing accretion in a cloud of supercooled water droplets. If the rate at which supercooled cloud drops impinge on an ice crystal is sufficiently large, the heat of fusion released during the freezing cannot be dissipated sufficiently rapidly and an ice-water mixture, or spongy ice, is deposited on the growing ice particle.…”

Section: Introductionmentioning

confidence: 99%

On the electrical effects that accompany the spontaneous growth of ice in supercooled aqueous solutions

Pruppacher¹,

Steinberger²,

Wang³

1968

J. Geophys. Res.

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Measurements revealed that the spontaneous growth of ice crystals in supercooled aqueous solutions is accompanied by electrical effects. These effects were investigated at supercoolings between 2 ø and 11øC and in various salt solutions with salt concentrations between 10 -6 and 10 -x mole liter-L Freezing potentials up to 15 volts and freezing currents as large as 0.1 gamp were observed. The magnitude of the freezing potentials varied only slightly with the growth rate of ice but varied strongly and systematically with the concentration of salt in solution, with the type of salt dissolved, and with the time elapsed after freezing was initiated. The variation of the freezing potential with time was characterized by a sharp rise of the freezing potential in the very initial stages of ice growth and by a subsequent slower decay, which depended on the type of solution. In solutions with salt concentration larger than 10 -x mole liter -x or smaller than 10 -6 mole liter% the freezing potential was negligibly small. Maximum pqtentials developed in solutions with concentrations between 10 -• and 10 -8 mole liter-L By comparing solutions of salts with a common anton, it was found that the freezing potentials varied only slightly with the type of cation. By comparing solutions of salts with a common cation, it was found that the freezing potential varied markedly with the type of anton and was largest in fluoride solutions and smallest in iodide solutions. Ammonium solutions developed freezing potentials with a sign opposite to that developed in alkali halide solutions. It was shown that the magnitude of the freezing potentials is directly correlated to the electronegativity of the elements in solution. A comparison is drawn between the electrical effects observed during the spontaneous freezing of aqueous solutions and the electrical effects that develop when ice grows in aqueous solutions at a rate that is about 10 • times smaller, as is the case in a Workman-Reynolds type experiment. Some speculations are given about the significance of the observed electrical effects to thunderstorm electricity. measured the electrical effects that occurred during solidification of melted ionic, crystalline substances, such as KC1, NaC1, AgC1, KBr, and KI. Electrification accompanying the freezing of dilute aqueous solutions was studied by Workman and Reynolds [1948, 1950], Schaefer [1950], Backmann [1952], Gill and Al/rey [1952], Gill [1953], B. Gross [1954], Lodge et al. [1956], Heinmets [1962], Parreira and Eydt [1965], and G. W. Gross [1965]. According to these workers, the freezing potentials can be explained in terms of a potential barrier at the ice-solution interface and the probabilities for the different ions in solutions to jump over this barrier. During the growth of ice, the ice-solution interface behaves like a semi permeable membrane, allowing one kind of charge to pass through more readily than the other, thus causing an excess charge in the solid and an excess charge of the same magnitude but opposite sign in the liq...

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“…The experimental results described above should be compared with those of Latham and Miller [4]. These workers reported that the main factors governing the charging of an ice sphere moving through natural snow crystals were the surface roughness of the sphere and the speed with which the sphere was whirled through the air.…”

Section: Discussionmentioning

confidence: 95%

“…Only a few experimental measurements have been reported of the charges that an ice sphere can acquire when it moves through a cloud of natural ice crystals or supercooled droplets. Latham and Miller [4] investigated the charges acquired by different ice spheres after they had been rotated at various speeds through natural snowfall. Ice spheres with smooth surfaces were found to acquire a positive charge, but spheres with rough surfaces acquired much larger negative charges which increased in magnitude as the surface roughness of the sphere was increased.…”

Section: Introductionmentioning

confidence: 99%

FACTORS AFFECTING THE ELECTRIC CHARGE ACQUIRED BY AN ICE SPHERE MOVING THROUGH NATURAL SNOWFALL¹

Burrows¹,

Scott²

1967

Mon. Wea. Rev.

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The factors affecting the electric charge acquired by an ice sphere moving through natural snowfall have been investigated experimentally. When graupel particles were in the air the sphere always received a positive charge. If graupel was not present the sign of the charge appeared to be related to the direction of the atmospheric electric field.When the field was directed downwards the ice sphere received negative charge, and when the field was directed upwards the sphere received positive charge.The results are explained in terms of the direct transfer to the ice sphere of some of the net charge on the ice particles in the air making a glancing contact with the ice sphere. The charges that an ice sphere received by this mechanism appeared to be much larger than any charges that might have been generated by asymmetrical rubbing between the ice particles in the air and the surface of the ice sphere.

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The Role of Ice Specimen Geometry and Impact Velocity in the Reynolds-Brook Theory of Thunderstorm Electrification

Cited by 27 publications

References 0 publications

Role of relaxation and contact times in charge separation during collision of precipitation particles with ice targets

Role of relaxation and contact times in charge separation during collision of precipitation particles with ice targets

On the electrical effects that accompany the spontaneous growth of ice in supercooled aqueous solutions

FACTORS AFFECTING THE ELECTRIC CHARGE ACQUIRED BY AN ICE SPHERE MOVING THROUGH NATURAL SNOWFALL¹

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The Role of Ice Specimen Geometry and Impact Velocity in the Reynolds-Brook Theory of Thunderstorm Electrification

Cited by 27 publications

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Role of relaxation and contact times in charge separation during collision of precipitation particles with ice targets

Role of relaxation and contact times in charge separation during collision of precipitation particles with ice targets

On the electrical effects that accompany the spontaneous growth of ice in supercooled aqueous solutions

FACTORS AFFECTING THE ELECTRIC CHARGE ACQUIRED BY AN ICE SPHERE MOVING THROUGH NATURAL SNOWFALL1

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FACTORS AFFECTING THE ELECTRIC CHARGE ACQUIRED BY AN ICE SPHERE MOVING THROUGH NATURAL SNOWFALL¹