So why is relative humidity misleading?
The answer is that more moisture can be present in warm air than in cold. Some people like to say warm air can hold more moisture than cold air. While that’s not scientifically correct, it is a convenient way to think about it.
What that means is warm air at 30 percent relative humidity and cold air at 60 percent relative humidity may actually have the same amount of water in the air.
So, while the cold air sounds moist, it might be pretty dry – just what the Flu likes.
Absolute humidity is expressed in weight of water, grams or pounds, in a volume of air, such as a cubic meter or yard. The higher the reading the wetter. The wetter the less likely of catching the Flu
“In some areas of the country, a typical summer day can have four times as much water vapor as a typical winter day – a difference that exists both indoors and outdoors,” “Consequently, outbreaks of influenza typically only occur in winter when low absolute humidity conditions strongly favor influenza survival and transmission.”