I’m really confused because the overall stated level on the weather app is 74%, which makes me think there’s lots of water in the air. Doesn’t seem right as it’s cold but also not foggy and clear as day.
I’ve had a mildew problem and I want to open the windows to keep airing out the room more often, but I don’t want to let in any added moisture.
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Humidity is relative to the temperature of the air. That’s why it’s called relative humidity. Hot air can hold a lot more water than cold air.
The dew point is the temperature at which the current amount of water in the air would be 100% humidity, ie dew would form on surfaces, it would be foggy, or it would rain/snow.
Inside vs outside, the absolute amount of water in the air would be about the same, but since it’s so much warmer inside due to heating, the relative humidity drops. Opening the window would let the heat out, and relative humidity would decrease, but you would get very cold. And any water that you added to the air through either a humidifier or breathing would be lost to the outside.
The short version is winter is so dry because the air holds less water, and we heat our homes without adding water to the air, resulting in low relative humidity in out homes.
Fun fact: air conditioning was invented to remove moisture from the air, and the comfort from cooling was an unintended side effect.
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