Here in Washington, DC, we often have high humidity days. In the summertime, it makes the days rather miserable. A 90F day with high humidity in Washington is less comfortable than a 100F day in Phoenix with little or no humidity.
I can understand that.
Recently, I was talking with a co-worker from South Dakota. He was complaining that the winter air here is too humid, and it makes it seem colder here when it’s 25F than it does back in SD when it’s 10F (with no humidity).
I don’t understand that.
How does humidity always make the air less comfortable to be in? If it makes warm air feel hotter, shouldn’t it make cooler air more mild, rather than feeling colder?
I play golf through the winter. A 40 degree day is quite pleasant if the air is dry enough. A 40 degree day when the air is damp, on the other hand, is simply miserable. Your hands freeze, your face freezes,…
Moisture transpiring off your skin helps you feel cool when it’s hot out. This is why it feels hotter when it’s humid – you can’t sweat as easily/efficiently. By the same token, cold, moist air makes you feel colder, because its as if the air is sweating for you, drawing warmth off of your skin through transpiration. Remember: dry=warm, that’s why you wear wicking underclothes when you ski, etc.
Then why do we all use humidifiers in our homes in the winter to help cut down on our heating bill? Granted, there are health benefits to moist air over dry air but we’re not talking about that. This is strictly a comfort question right?
In that case it should be mentioned that there is a definite “comfort zone” where we feel most comfortable with respect to humidity. I think this is between 40%-50%. Below that, moisture is drawn away from our skin causing us to feel cooler (refrigeration via evaporation). Above 50%, I suppose the air could be so moist that it collects on your skin, causing you to become damp. In cold weather this is certainly contraindicated but I seriously doubt that it gets about 50% RH here in DC in the winter.
Slight nitpick – You sweat just as much when the humidity is at 100% as you do when it’s at 0%. The difference is that sweat cools you through evaporation. (try putting rubbing alcohol. on your skin, same idea) at 100% humidity you’re not going to get much, if any, evaporation from your skin into the air. No evaporation, no cooling.
Thermal mass. Moisture laden air can draw more heat from a warm body than dry air. To illustrate thermal mass, stick your left hand into 38 degree refrigerator. Now stick your right hand in a bucket of water that’s 38 degrees. They’re both the same temperature. Which one feels colder?
Humidifiers in homes are thought to have more of an affect on health, such as preventing bloody noses and sinus infections from excessive dryness. This has mixed results, because dust-mites flourish in humidities above 50%, and are a common source of alergic irritation. The health effects of humidity seem to be a what-you-are-used-to thing, or maybe there is some form of adaptation, because people complain mostly when the humidity is different, not when it is high or low.
Air is also dried by normal air conditioning systems, and they are used some times to remove moisture from high humidity cold air in hospitals, clean rooms, computer rooms, and any other place where humidity has to be within a certain, fairly tight range. It is expensive even in moderate climates.
The humidity makes the cold air feel colder. If you kept the air in your house 45 degrees, making it more humid would make it seem colder. Also, the humidifier is increasing the humidity up to 20 to 40 percent. The humidity also helps reduce the electric shocks you get with dry air, and keeps your (well, my) skin from drying out.
