PRECIPITATION DEVELOPMENT AND ELECTRIFICATION IN FLORIDA THUNDERSTORM CELLS DURING CONVECTION AND PRECIPITATION/ELECTRIFICATION PROJECT

摘要

Precipitation development and electrification in Florida thunderstorms are observed using an instrumented aircraft and a multiparameter radar. 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, where the aircraft penetrated, as do electric fields in the range of tens of kilovolts per meter. In a cell with relatively weak updrafts, drops start to freeze at temperatures just below 0 degrees C. Although significant 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 electric fields measured by the aircraft in these cells are similar in magnitude to those in the weaker cell. but lightning is observed in these more vigorous cells. The net charge in convective regions at altitudes just above the aircraft penetration levels, 6-7 km, appears to be negative. [References: 76]