In a few weeks I’ll be visiting my parents in Pennsylvania. I was joking about this with my co-workers yesterday as we were complaining about the cold wind on an otherwise pleasant day: I’m not going to complain, I said, because before I know it I’ll be in Pennsylvania, complaining about how hot and humid it is!
One of my colleagues asked if it was very humid there. Oh, yes, I said, anyone who’s lived in the Northeastern US can tell you how bad the humidity is inland.
But both of us shared the same gut feeling: something is wrong there. Shouldn’t it be less humid as you get away from large bodies of water, not more? Why isn’t the humidity stifling down on the Jersey Shore and pleasantly low in Lancaster County? My guess was that the winds along the shore keep the humidity from building up, an idea which struck both of us as rather lacking in logic…
You can get high humidity when you have an absolute large amount of water in the air.
But you can also get high humidity when you have relatively smaller amounts of water, but relatively less air to mix it through (low pressure). This sounds odd , but you can forget the physics and understand that it works in practice by the air being responsible for carrying evaporated water away from your skin. With less air available at lower pressures you evaporate less water and feel sweaty.
And you can also get high humidity when you have relatively little water but the saturation point is low (low temperature). Generally maritime climates are more stable, so cooler in the tropics and at night, warmer in temperate zones and during the day.
Not sure about the relative pressures of the Eastern US.
Don’t forget the Great Lakes. Wind passes over the lakes, generally from the northwest, and sucks up a lot of moisture. Humidity ensues (and also lake-effect snow).
It sounds VERY odd. Barometric pressure changes over maybe a 10% range in common weather, and it is not usually that different between the Jersey shore and Lancaster, maybe more like 1% or 2%. And the regions where air pressure are the lowest in the CONUS, around the continental divide for example, are known for lower humidity than Florida, where they are higher (the main effect on pressure being altitude).
I think this explanation tells us something about compressed air lines always being wet, but doesn’t explain the OP.
I am not qualified to offer anything to the OP on this but I do have to question this statement (in bold).
The condensate on an air line would only happen when there is movement from a High pressure to a Low what i think of as a refrigeration effect.
The cold line then attracting moisture in the air to cling to the cold object.
Take a cold can of Blatzout and you have the same thing. Any moisture in the air will condensate on the outside of the cold can. You now have, “A REDNECK HYGROMETER”
I live at the Jersey shore and, believe me, its humid. It may not seem as bad because there is usually a breeze coming off the ocean from about 2:00 PM until into the night. While the breeze is cooler, it also carries lots of moisture with it. Without air conditioning sheets are always damp and mold grows on things in the closet. I lived in Pennsylvania and I’ll take the moist sea breeze any time. I think what is generally happening is that the jet stream retreats north in the summer allowing all the moist tropical air to infiltrate northward. Also, high pressure often sits for extended periods over Bermuda (ever hear of a Bermuda high?). The airmass rotation is clockwise and downward, drawing in warm, moist air from over the ocean and making it warmer as it compresses over the land. These things combine to make the thick enough to cut.
I meant the condensation inside the lines. Generally, if you compress ordinary ambient air much, it becomes supersaturated and the water condenses out when it can. This is because you are also compressing the water vapor, to a pressure above its equilibrium vapor pressure in contact with flat liquid water.
Actually, I got things backwards. While this phenomenon is real, it is inconsistent with Blake’s statement that having more air pressure to mix with water reduces the relative humidity.