A computational study of the relationships linking lightning frequency and other thundercloud parameters

In an effort to optimize the value of global-scale measurements obtained with the NASA/MSFC satelliteborne Lightning Imaging System (LIS), a simple computational model of thundercloud electrification has been developed, from which it is possible to derive crude relationships between lightning frequency f (which LIS will measure) and cloud parameters such as radar reflectivity Z, precipitation rate P, updraught speed w, cloud radius R, ice-crystal concentration i and graupel-pellet concentration Ng. Electric field-growth is assumed to occur via the non-inductive charging mechanism, for both Fletcher and Hallett-Mossop types of glaciation mechanisms. A simple criterion is used to distinguish between cloud-to-ground and intracloud lightning discharges. f is found to be especially sensitive to w in situations where, as updraught speed increases, the temperature at balance level, Tbal, of the upper boundary of the charging zone falls. In these circumstances N1 and the sizes of the ice hydrometeors are significantly increased, with a corresponding enhancement of the effectiveness of charge transfer. Over a wide range of conditions, f is found to be roughly proportional to the first power of the parameters R1NiNg and Z and (in some circumstances) to at least the sixth power of w. the relationship between f and P depends critically on whether or not w and Tbal are strongly linked. Hallett-Mossop glaciation is capable of producing inverted-polarity lightning from thunderclouds; Fletcher glaciation is not.

[1]  J. Hallett,et al.  Production of secondary ice particles during the riming process , 1974, Nature.

[2]  S. Rutledge,et al.  Positive Cloud-to-Ground Lightning in Mesoscale Convective Systems , 1990 .

[3]  R. F. Griffiths,et al.  Electrical corona from ice hydrometeors , 1974 .

[4]  R. Treumann,et al.  Observation of nonlinear-wave decay processes in the solar wind by the AMPTE IRM plasma-wave experiment. Technical report , 1987 .

[5]  Tsutomu Takahashi,et al.  Riming Electrification as a Charge Generation Mechanism in Thunderstorms , 1978 .

[6]  R. F. Chisnell,et al.  Ice particle multiplication in cumulus clouds , 1976 .

[7]  R. Orville.  Winter lightning along the East Coast , 1990 .

[8]  W. David Rust,et al.  Electrical and Kinematic Structure of the Stratiform Precipitation Region Trailing an Oklahoma Squall Line. , 1991 .

[9]  W. David Rust,et al.  Lightning and precipitation history of a microburst‐producing storm , 1988 .

[10]  S. E. Reynolds,et al.  THUNDERSTORM CHARGE SEPARATION , 1957 .

[11]  J. Latham.  The electrification of thunderstorms , 1981 .

[12]  N. Fletcher.  The Physics of Rainclouds , 1962 .

[13]  J. Latham,et al.  Calculations of electric field growth, field structure and charge distributions in thunderstorms , 1977 .

[14]  J. A. Crabb,et al.  Corona from colliding drops as a possible mechanism for the triggering of lightning , 1974 .

[15]  W. Cooper,et al.  Field Evidence Supporting Quantitative Predictions of Secondary Ice Production Rates , 1987 .

[16]  J. Latham,et al.  A numerical study of thunderstorm electrification: Model development and case study , 1991 .

[17]  E. R. Jayaratne,et al.  Laboratory studies of the charging of soft hail during ice crystal interactions , 1983 .

[18]  R. Farley,et al.  An intracloud lightning parameterization scheme for a storm electrification model , 1992 .

[19]  M. Chong,et al.  The June 22 tropical squall line observed during COPT 81 experiment: Electrical signature associated with dynamical structure and precipitation , 1985 .