Causes for Precipitation Increases in the Hills of Southern Illinois

Jones, Douglas M.A.; Huff, Floyd A.; Changnon, Stanley A., Jr.

Permalink

https://hdl.handle.net/2142/77785 Copy

Description

Title

Causes for Precipitation Increases in the Hills of Southern Illinois

Author(s)

• Jones, Douglas M.A.
• Huff, Floyd A.
• Changnon, Stanley A., Jr.

Issue Date

1974

Keyword(s)

• Cloud condensation nuclei
• convection
• diurnal differences
• hill effect
• Illinois
• precipitation
• radar echoes
• wind

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.

Publisher

Illinois State Water Survey

Series/Report Name or Number

Report of Investigation (Illinois State Water Survey) RI-075

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/77785

Copyright and License 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.

Owning Collections