28 FEBRUARY 2003
DATA SET PAGE 11: ANNUAL HUMIDITY SUMMARY. Figure 2-11 is an
example of Data Set Page 11. Similar to the annual temperature summary (see Sample
Data Set Page 10, Figure 2-10), this chart depicts mean maximum and minimum values
of humidity ratio, plus the 1% maximum humidity ratio, along with its mean coincident
dry bulb temperature, summarized by calendar week. The chart uses two vertical axes:
on the left are the humidity ratio values and on the right is a temperature scale for the
mean coincident dry bulb temperature.
Suggestions for Use. W eekly humidity ratios are useful for understanding
the change of seasons at a given location and the probable high and low moisture
levels during a given week of the year. The display is helpful for planning humidity-
controlled storage projects and for understanding factors contributing to atmospheric
corrosion. Humidity also affects the deterioration rate of building materials and the
weathering of military equipment and structures exposed to the elements.
Designers. The values displayed here are based on the 30-year record. It
is important that designers not base equipment selection on the "highest" or "lowest"
recorded humidity at the station. That error would result in selecting oversized
equipment, which would increase costs and might result in control problems at other
than extreme conditions. Use design values on Data Set Page 1 (Figure 2-1) for
Construction and Operation Planners. The high and low humidity ratios
shown for each week seldom occur in the same year. Keep in mind that these are mean
values that are useful for understanding the typical range of humidity ratio in a given
week. The difference does not represent the actual day-night humidity ratio swing in a