The 80 - 80 Rule...and other facts about evaporative cooling?
During hot weather, did you know that whenever the air temperature is above 80oF the relative humidity is virtually always below 80%? And that when the air temperature is below 80oF,(i.e, early morning, evening, and night) that the relative humidity is always above 80%. It may seem hard to believe, but it is a fact. For example, from June through August of 1999 in Gainesville, Georgia, when the air temperature was above 80oF, 99.5 percent of the time the relative humidity was below 80%....99.9 percent of the time the relative humidity was below 85%! This is not only true in Gainesville but throughout most of the poultry-growing areas of the U.S.