SEASONAL VARIATIONS IN HOURLY DEWPOINT TEMPERATURE
The accompanying image is a plot of the variations in the hourly
dewpoint temperatures (or dewpoint for short) observed at the weather
station throughout the year. The average dewpoint for each hour
of the day at the station was computed from the set of observed hourly
dewpoints for the given station for the 30 years from 1971-2000.
The horizontal axis displays the day of the year, while the vertical
axis represents the hour of the day (in the 24-hour format and in
Central Standard Time). Lines of equal dewpoints (also know as
isodrostherms) were computer generated and displayed using
a krieging technique.
By selecting any hour of the day and moving horizontally, the seasonal variations in that hour's dewpoint can be seen. The lowest dewpoints typically occur in the mid winter (days 1-50 = Jan-Feb) when the air temperatures are also low, while the highest dewpoints are found in mid summer (days 180-210= July) when the air is warm.
Some small daily variations in the dewpoint are apparent, especially
during the summer. Move vertically along any day, keeping
parallel to the vertical axis. Slightly higher hourly dewpoints
typically are found during the afternoon and evening (centered at
approximately 1800 or 6 PM CST), while the lower dewpoints are found
during the night.
Prepared by Edward J. Hopkins, Ph.D., Assistant State Climatologist
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Latest revision: 25 April 2004
Comments on the web page ... SCO Web Administrator
URL Address: http://www.aos.wisc.edu/~sco/stations/ann_hrly_dewpt.html