The featured chart is an attempt to illustrate differences in over night cooling rates by showing a composite profile of temperature for a three hour period prior to reaching a freezing temperature. The airport weather sensor in Des Moines is in a very urban area, while the Waterloo sensor is on the edge of town. The slope of these two lines is slightly different showing a faster cooling rate for Waterloo. This is an illustration of the "heat island" effect that is caused by having lots of heat retaining buildings and pavement nearby the weather sensor.

Voting:
Good = 16
Bad = 3

Tags:   heatisland  

The past two mornings have seen rather chilly temperatures with record lows set in Mason City and Ottumwa. The featured map presents the lowest temperature reported since the first of August. While some locations have dipped into the 30s, the major urban centers of Des Moines, Council Bluffs, and Iowa City have barely breached 50 degrees. This is a classic urban heat island effect of having lots of warm buildings and concrete slowing the rate of cooling overnight.

Voting:
Good = 15
Bad = 3

Tags:   heatisland  

The featured chart displays the hourly average temperature difference by year between Des Moines and Waterloo. The chart nicely shows the effect of having a weather sensor in an urban area (Des Moines) versus a more rural one (waterloo). Notice how Des Moines is much warmer during the night time than during the daytime. This is probably a result of the Urban Heat Island Effect. If you are into warm nights, living in Des Moines is your best bet in Iowa.

Voting:
Good = 30
Bad = 8

Tags:   heatisland