The Geographic Society of Chicago, Bulletin No. 4 The Weather and Climate of Chicago

Abstract

MESSRS. Cox AND ARMINGTON have made a statitical study of the climate of Chicago of extraordinary detail. The result is valuable as a book of reference, but cannot be described as easy reading, chiefly owing to one hundred and forty-five tables intercalated in the text. Records of temperature extend back to 1830 and of rainfall to 1843, but the series are not homogeneous, there being several changes even in the shorter period 1871 to 1911, which is adopted for normal values. Normals, however, are not regarded as so important as the occurrences of abnormal conditions and rapid variations which render the climate healthful and invigorating—and with a temperature range from 16° to + 103° F. there is abundant room for rapid changes. The extremes would he even greater but for the near neighbourhood of Lake Michigan, as is well shown by a study of the lake breezes, and by temperature records at different distances from the shore. The abnormal periods are further considered, not merely locally, but as part of the weather of the whole States, and this aspect is illustrated by reproductions of the daily synoptic charts, unfortunately sometimes so small as to be almost undecipherable. Full use is made of isopleth diagrams for exhibiting hourly variations; a feature with less to recommend it is the replacement of departures from normal temperature by accumulated departures, which are said to be “more vivid”—though it is not self-evident that an “accumulated” departure of + 1262° conveys more to the mind than a mean departure of + 3½°.