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Title:Causes for Precipitation Increases in the Hills of Southern Illinois
Author(s):Jones, Douglas M.A.; Huff, Floyd A.; Changnon, Stanley A., Jr.
Subject(s):Cloud condensation nuclei
diurnal differences
hill effect
radar echoes
Abstract:Studies involving precipitation in Illinois have shown the presence of 10 to 15 percent more precipitation in the average annual precipitation pattern in the Shawnee Hills area of southern Illinois than in nearby ftatlands. Three methods differing in scale and time were used to delineate the hill anomaly and to determine the reasons for it. First, a series of climatic studies of precipitation distribution considering daily, monthly, and seasonal data for comparison of hill and fladand stations were performed during 1960-1963. Next, a 5-year project involving analysis of data from a special raingage network on the basis of individual rain periods, months, and seasons during 1965-1969 was planned to define the areal extent of the hill high. Finally, the results of these two studies were used to design a 1-month field study involving a weather radar, 3 cloud cameras, 5 weather (temperature-humidity) stations, 1 pilot balloon site, and aircraft sampling flights. Results of the three major studies show that the hill enhancement of precipitation is the addition of moisture due to greater evapotranspiration from the forested hills and the convergent wind field created over the western hills caused by the configuration of the hills and valleys.
Issue Date:1974
Publisher:Illinois State Water Survey
Series/Report:Report of Investigation (Illinois State Water Survey) RI-075
Genre:Technical Report
Publication Status:published
Peer Reviewed:peer reviewed
Rights Information:Copyright, University of Illinois Board of Trustees. All rights reserved. This document is a product of the Illinois State Water Survey, and has been selected and made available by the Illinois State Water Survey and the University Library, University of Illinois at Urbana-Champaign. It is intended for research and educational use, and proper attribution is requested.
Date Available in IDEALS:2015-05-28

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