PRECIPITATION DEVELOPMENT AND ELECTRIFICATION IN FLORIDA THUNDERSTORMCELLS DURING CONVECTION AND PRECIPITATION ELECTRIFICATION PROJECT/

Precipitation development and electrification in Florida thunderstorms are observed using an instrumented aircraft and a multiparameter rada r. A low concentration of raindrops initially develops in the updraft, and these raindrops begin to freeze when they are carried above the 0 degrees C level. High concentrations of ice particles and downdrafts soon appear in the -5 degrees to -10 degrees C regions of the cloud, w here the aircraft penetrated, as do electric fields in the range of te ns of kilovolts per meter. In a cell with relatively weak updrafts, dr ops start to freeze at temperatures just below 0 degrees C. Although s ignificant electric fields are measured by the aircraft, no lightning is observed in this cell. In more vigorous cells, drops first begin to freeze at temperatures between -5 degrees C and -10 degrees C. The el ectric fields measured by the aircraft in these cells are similar in m agnitude to those in the weaker cell. but lightning is observed in the se more vigorous cells. The net charge in convective regions at altitu des just above the aircraft penetration levels, 6-7 km, appears to be negative.