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Abstract
Icing experiments are described in which artificial hailstones have been grown in a vertical wind tunnel at a relative speed of 18 m sec−1 at temperatures between −5 and −20C, and with liquid water contents of 2 and 4 gm −3. The results show that air bubbles can be characterized by log-normal distributions of their diameters with the mean sizes primarily dependent on the liquid water content. Doubling the liquid water content led to larger but fewer bubbles, while lowering the air temperature led to smaller but more numerous bubbles. Thus, it is expected that bubble size distributions and concentrations may be the key to the interpretation of hailstone history.
Abstract
Icing experiments are described in which artificial hailstones have been grown in a vertical wind tunnel at a relative speed of 18 m sec−1 at temperatures between −5 and −20C, and with liquid water contents of 2 and 4 gm −3. The results show that air bubbles can be characterized by log-normal distributions of their diameters with the mean sizes primarily dependent on the liquid water content. Doubling the liquid water content led to larger but fewer bubbles, while lowering the air temperature led to smaller but more numerous bubbles. Thus, it is expected that bubble size distributions and concentrations may be the key to the interpretation of hailstone history.
The Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is to compare the results of the very high resolution Met Office weather forecasting model with detailed observations of the early stages of convective clouds and to use the newly gained understanding to improve the predictions of the model.
A large array of ground-based instruments plus two instrumented aircraft, from the U.K. National Centre for Atmospheric Science (NCAS) and the German Institute for Meteorology and Climate Research (IMK), Karlsruhe, were deployed in southern England, over an area centered on the meteorological radars at Chilbolton, during the summers of 2004 and 2005. In addition to a variety of ground-based remote-sensing instruments, numerous rawinsondes were released at one- to two-hourly intervals from six closely spaced sites. The Met Office weather radar network and Meteosat satellite imagery were used to provide context for the observations made by the instruments deployed during CSIP.
This article presents an overview of the CSIP field campaign and examples from CSIP of the types of convective initiation phenomena that are typical in the United Kingdom. It shows the way in which certain kinds of observational data are able to reveal these phenomena and gives an explanation of how the analyses of data from the field campaign will be used in the development of an improved very high resolution NWP model for operational use.
The Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is to compare the results of the very high resolution Met Office weather forecasting model with detailed observations of the early stages of convective clouds and to use the newly gained understanding to improve the predictions of the model.
A large array of ground-based instruments plus two instrumented aircraft, from the U.K. National Centre for Atmospheric Science (NCAS) and the German Institute for Meteorology and Climate Research (IMK), Karlsruhe, were deployed in southern England, over an area centered on the meteorological radars at Chilbolton, during the summers of 2004 and 2005. In addition to a variety of ground-based remote-sensing instruments, numerous rawinsondes were released at one- to two-hourly intervals from six closely spaced sites. The Met Office weather radar network and Meteosat satellite imagery were used to provide context for the observations made by the instruments deployed during CSIP.
This article presents an overview of the CSIP field campaign and examples from CSIP of the types of convective initiation phenomena that are typical in the United Kingdom. It shows the way in which certain kinds of observational data are able to reveal these phenomena and gives an explanation of how the analyses of data from the field campaign will be used in the development of an improved very high resolution NWP model for operational use.