Abstract

This Technical Note is a case study of one of the storms examined in the 1975 field season of the National Hail Research Experiment, during which the two primary observing instruments were the CP-2 10 cm radar and the South Dakota School of Mines and Technology armored T-28 aircraft that had just... Show moreThis Technical Note is a case study of one of the storms examined in the 1975 field season of the National Hail Research Experiment, during which the two primary observing instruments were the CP-2 10 cm radar and the South Dakota School of Mines and Technology armored T-28 aircraft that had just been instrumented with new cloud physics probes. A complex multi-cell thunderstorm was penetrated with the armored T-28 aircraft. The T-28 carried a comprehensive suit of instruments to measure specific, critical parameters in the thunderstorm. The instrumentation package included a foil impactor for measuring particles larger than 1 mm, a Particle Measuring Systems (PMS) two-dimensional cloud probe for measuring 25 lim to 1 mm diameter particles, and a PMS Forward Scattering Spectrometer Probe (FSSP) for measuring droplets 2-30 lpm diameter. The National Hail Research Experiment's (NHRE) CP-2 radar was located in a prime position to acquire optimum data on this storm. A Doppler processor was integrated into the CP-2 system. The location and motion of the storm were fortuitous in that the storm moved almost directly away from the radar, and 65�� to the right of the environmental winds. The data set is examined in detail. The key to understanding the data lies in dividing the storm into its component cells (parts) and examining the data in the context of cell lifetimes. Thirty-nine cells were delineated as part of the storm which lasted over two hours. Six of these cells were penetrated by the T-28, two of them twice. A conceptual model is developed by considering the total interactive series of cells and the detailed measurements within specific cells relative to the total radar study and the detailed radar analysis of each cell. Using the analyzed data, cross sections are developed to show the spatial and temporal parameter evolution through the life of a typical cell in a multicell storm. Evidence exists for the recirculation of ice crystals in areas of subdued convection and downdrafts to allow time for growth of cloud elements to hail embryo sizes followed by subsequent diffusion into updraft areas where the ingredients for rapid growth of these embryos to hail sizes exist. Show less