Thermal Design and Analysis of the Apollo Lunar Radioisotopic Heater.

Klett, R.D.

doi:10.2172/4711931

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“…No reliable measurements have been made inside thunderclouds, for technical reasons which have been examined in detail by Fitzgerald (1965). Calculations of ion-flow to cloud particles have been made by several workers although, as pointed out by Klett (1971), most studies have excluded either the role of diffusion or of the electric forces in the trapping process. The general case, with diffusion and conduction operating together to remove ions, has been treated by Gunn (1956) and Phillips (1967) simply by adding the fluxes resulting from the two limiting cases.…”

Section: Introductionmentioning

confidence: 99%

The ionic conductivity of electrified clouds

Griffiths

Latham

Myers

1974

Quart J Royal Meteoro Soc

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SUMMARYCalculations have been made, on the basis of the ionic balance equations derived by Phillips (1967), of the electrical conductivity of clouds in the presence, and in the absence, of secondary ion production resulting from corona.In weakly electrified clouds -no corona -the immobilization of ions on cloud droplets resulting from diffusional capture results in a reduced ionic concentration and conductivity. The normalized conductivity 1 (the ratio of the in-cloud value to the clear-air value at the same altitudez) was calculated for three different cloud types (cumulus congestus,-strato-cumulus and fog) as a function of Z, liquid water content L, droplet charge Q and field strength E. 3, was found to be very sensitive to variations in L and E, but only slightly affected by changes in Z, Q and the manner in which the charge is distributed over the size-spectrum. For example, when E = 0 I possessed the values 0.034 and 0.17 in-a cumulus congestus cloud for L = 0.5 gm/m3 and 0.1 gm/m3 respectively, whereas when E = 90 kV/m I was 1.5 x and 7.6 x respectively for the same two values of L.The experimental measurements of corona onset fields and currents from ice hydrometeors, E, and i, respectively, made by Griffiths and Latham (1974) were used to calculate the normalized conductivity within strongly electrified clouds. Corona from ice provides a copious supply of positive and negative ions which causes I to increase from between to greater than 1 when E, is achieved. The value of 1 once corona is initiated depends on L and the concentration of corona sites, J. In this situation altitude Z plays an important role because E, decreases quite rapidly with decreasing pressure. For example, with a typical distribution of temperature and pressure within a thundercloud, corona will be initiated from hailstones at E, = 720 kV/m if Z = 2.5 km (0" C) and 540 kV/m at 5 3 k-m (-18" C); the corresponding values of E, for snowflakes are 540 and 390 kV/m respectively. At 2.5 km I is slightly higher than and lower than 10 respectively, as L is increased from 1 to 5 gm/m3 with J =

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Section: Introductionmentioning

confidence: 99%