Influence of meteorological conditions on the intensity and form of the urban heat island effect in Regina

This study investigates the influence of meteorological conditions on the i ntensity and spatial configuration of the urban heat island effect in Regin a, Saskatchewan. A sample of 31 nocturnal heat island intensities measured via automobile surveys averages 3 degreesC, with a maximum intensity reachi ng 7.5 degreesC On nights with clear skies and light winds, heat island mor phology in Regina is characterized by a clearly defined cliff plateau, and peak. Regression analysis reveals that hear island intensities are highly s ensitive to changes in wind conditions, and relatively insensitive to chang es in humidity and atmospheric pressure. However, when antecedent weather c onditions preceding each heat island event are included in the analysis, cl oud cover supersedes wind speed as a more important control on heat island intensity. Daytime and postsunset cloud cover explain 20 percent more varia nce in the ensuing nocturnal heat island intensities than do daytime and po st-sunset wind speeds. This result challenges the widely-held notion that w ind speed is a more important heat island control than sky cover.