A Singularity in Clear-Day Frequencies in the North-Central Region

Open Access
Publisher Website
Google Scholar
Abstract
The frequency that clear days (0.0 sky cover) occur within each week of the year was determined for 14 North-Central region stations. A remarkably consistent and nearly region-wide feature of a high frequency of clear days was found to be concentrated in the week of 27 September–3 October. This period is probably an integral part of the Midwestern Indian Summer and follows by about one week the frequently referred to autumnal change of season date.