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Browsing by Author "Sinclair, P. C., author"

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    The genesis and development of deep convective storms
    (Colorado State University. Libraries, 1983-01) Sinclair, P. C., author; Purdom, J. F. W., author; Cooperative Institute for Research in the Atmosphere (Fort Collins, Colo.), publisher
    During the summer of 1980, NESS sponsored a research aircraft field program that combined research aircraft flights with rapid scan GOES imagery. The purpose of the research program was to provide a better understanding of the natural mechanisms that lead to the development of deep convective storms through integration and analysis of those special data sets. Data were taken during the field program with the goal of providing an in-depth understanding of the fundamental mechanism - arc cloud line interactions - that lead to the development of deep convection. The experiment provided a unique data base from which the convective storm's mesoscale flow field (dynamic and thermodynamic properties) could be documented by in-situ measurements and near simultaneous GOES visible and infrared data. Several arc clouds were penetrated on three separate GOES rapid scan imaging days, and representative results from those penetrations are given in the text. It is hoped that the improvement in knowledge gained from this experiment will lead to a better understanding of mesoscale dynamics, which is of great importance for the development of improved short-range forecasting techniques.
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    Vortex structure and dynamics of Florida Keys waterspouts: 1974 field experiment, final report
    (Colorado State University. Libraries, 1974) Sinclair, P. C., author; Department of Atmospheric Science, Colorado State University, publisher
    From direct penetrations of the waterspout funnel by specially instrumented aircraft, a quantitative description of the dynamic-thermodynamic structure of the waterspout has been developed. The Navier-Stokes equations of motion for the waterspout vortex are simplified by an extensive order of magnitude analysis of each term in the equations. The reduced set of equations provides a realistic mathematical model of the waterspout vortex. Further simplification shows that the cyclostrophic-Rankine combined vortex model accounts for, on the average, approximately 63% of the measured pressure drop from the environment to the waterspout core. The penetration measurements show that the waterspout funnel consists of a strong rotary and vertical field (radial component is smaller) of motion which results in a combined flow pattern similar to that of a helical vortex. In general, the measurements indicate that this one-cell vortex structure is the dominate configuration. However, several penetrations suggest reduced positive vertical velocities near the funnel core, and in one case, a downdraft core with vertical velocity of -0.8 msec-1. These measurements indicate that waterspout vortex may in some stages of development have a structure more closely described by the two-cell vortex such as discovered by Sinclair (1966, 1973) for the dust devil vortex. The temperature and pressure structure show that the waterspout, like the dust devil, is a warm core (ΔT = 0.1 to 0.5°C), low pressure (ΔP = -0.6 to -8.4 mb) vortex. All aircraft penetrations of the visible funnels were made within 150 m of cloud base at speeds of 55-65 msec-1.