An examination of the convective charging hypothesis: Charge structure, electric fields, and Maxwell currents

[1] An examination of the convective charging hypothesis is undertaken using our three-dimensional (3D) storm electrification model (SEM). In an attempt to cover the range of storm conditions over which the convective mechanism might be expected to operate, two storms are simulated: a small, weak storm and a larger, severe storm. Elements of the model relevant to the convective hypothesis are the full treatment of small ions, including attachment to hydrometeors, the inclusion of field-dependent surface point discharge, and the components of the Maxwell current. For comparison purposes, each storm is also simulated using a noninductive mechanism. Results from both the small and large storm simulations using convective-only charging indicate disorganized, weak electrical structures during the mature and dissipating stages. Conversely, the use of noninductive charging produces strong electrification in both storms. Maxwell current analysis shows that, for the most part, currents within the storm are dissipative and that the cloud acts as a barrier to the external conduction current when convective-only charging is considered. For the noninductive simulations, the Maxwell current is that of a generator. The treatment of small ions and their attachment to hydrometeors accounts for the formation of screening layers; thus this aspect of the convective charging mechanism still plays an important role in the modeling of thunderstorm charge structures. However, since the convective charging hypothesis, by itself, is unable to produce significant charging or strong electric fields in either simulated cloud, we conclude that it is not a viable mechanism for thunderstorm electrification.

[1]  L. Loeb,et al.  Fundamental Processes of Electrical Discharge in Gases , 1940, Nature.

[2]  A. Arakawa.  Computational design for long-term numerical integration of the equations of fluid motion: two-dimen , 1997 .

[3]  J. Helsdon.  Chaff Seeding Effects in a Dynamical-Electrical Cloud Model , 1980 .

[4]  John H. Helsdon,et al.  A numerical modeling study of a Montana thunderstorm: 2. Model results versus observations involving electrical aspects , 1987 .

[5]  H. D. Orville,et al.  Bulk Parameterization of the Snow Field in a Cloud Model , 1983 .

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

[7]  T. Clark,et al.  Severe Downslope Windstorm Calculations in Two and Three Spatial Dimensions Using Anelastic Interactive Grid Nesting: A Possible Mechanism for Gustiness , 1984 .

[8]  J. Smagorinsky,et al.  GENERAL CIRCULATION EXPERIMENTS WITH THE PRIMITIVE EQUATIONS , 1963 .

[9]  Jerry M. Straka,et al.  A lightning parameterization for numerical cloud models , 2001 .

[10]  Douglas K. Lilly,et al.  ON THE COMPUTATIONAL STABILITY OF NUMERICAL SOLUTIONS OF TIME-DEPENDENT NON-LINEAR GEOPHYSICAL FLUID DYNAMICS PROBLEMS , 1965 .

[11]  Ronald B. Standler,et al.  Effects of coronae on electric fields beneath thunderstorms , 1979 .

[12]  R. Jayaratne.  Thunderstorm electrification mechanisms , 2003 .

[13]  J. A. Musser,et al.  Maxwell currents under thunderstorms , 1982 .

[14]  John H. Helsdon,et al.  An examination of thunderstorm‐charging mechanisms using a two‐dimensional storm electrification model , 2001 .

[15]  P. Smolarkiewicz,et al.  The multidimensional positive definite advection transport algorithm: further development and applications , 1986 .

[16]  Terry L. Clark,et al.  Numerical simulations with a three-dimensional cloud model: Lateral boundary condition experiments and multicellular severe storm simulations , 1979 .

[17]  Chin-Shan Chiu,et al.  Numerical study of cloud electrification in an axisymmetric, time-dependent cloud model , 1978 .

[18]  J. A. Chalmers,et al.  On Wilson's theory of the collection of charge by falling drops , 1944 .

[19]  S. Rutledge,et al.  A Modeling Study on the Early Electrical Development of Tropical Convection: Continental and Oceanic (Monsoon) Storms , 1994 .

[20]  James E. Dye,et al.  Early electrification and precipitation development in a small, isolated Montana cumulonimbus , 1986 .

[21]  D. Lilly.  On the numerical simulation of buoyant convection , 1962 .

[22]  R. Gunn,et al.  DIFFUSION CHARGING OF ATMOSPHERIC DROPLETS BY IONS, AND THE RESULTING COMBINATION COEFFICIENTS , 1954 .

[23]  James D. Klett,et al.  Ion Transport to Cloud Droplets by Diffusion and Conduction, and the Resulting Droplet Charge Distribution , 1971 .

[24]  B. Vonnegut.  The Atmospheric Electricity Paradigm , 1994 .

[25]  T. Clark.  A small-scale dynamic model using a terrain-following coordinate transformation , 1977 .

[26]  R. Gunn,et al.  THE HYPERELECTRIFICATION OF RAINDROPS BY ATMOSPHERIC ELECTRIC FIELDS , 1956 .

[27]  A comparison of 3D model results with observations for an isolated CCOPE thunderstorm , 1992 .

[28]  B. Vonnegut,et al.  PRELIMINARY ATTEMPTS TO INFLUENCE CONVECTIVE ELECTRIFICATION IN CUMULUS CLOUDS BY THE INTRODUCTION OF SPACE CHARGE INTO LOWER ATMOSPHERE , 1958 .

[29]  C. Saunders,et al.  A Review of Thunderstorm Electrification Processes , 1993 .

[30]  J. Klett,et al.  Convective electrification of clouds , 1976 .

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

[32]  C. Scavuzzo,et al.  Convective electrification of clouds: A numerical study , 1997 .

[33]  P. Smolarkiewicz.  A Fully Multidimensional Positive Definite Advection Transport Algorithm with Small Implicit Diffusion , 1984 .

[34]  V. Mazur,et al.  Model of electric charges in thunderstorms and associated lightning , 1998 .