Dew Point: Vent Check

You already have the readings. This tells you what they mean. Type in what your own thermometer and hygrometer say — for this room, and for the air you are thinking of letting in. Nothing here is measured by the phone and nothing is fetched from a weather service. There is no network code in this app at all. Compare rooms by moisture, not percent. Relative humidity moves with temperature even when the water does not. Outside at 5 °C and 90 % holds about half the water of a room at 21 °C and 60 % — so opening the window in winter dries the room, and the percentages say the opposite. Both states sit on one axis in grams of water per kilogram of dry air, and the answer is a direction with a size, not a number to interpret. What the room becomes if you vent. Slide how much of the other air to let in and the mixed state moves between the two: its temperature, its humidity, its dew point. Water mass and heat are what carry over when two airs meet, so the mixed temperature is recovered from those rather than averaged. Nothing else in this category will show you the result of the mix. Every surface has its own margin. Water lands on the coldest thing in the room, not on the room. Name the window glass, the wall corner behind the wardrobe, the lens you are about to take outside, the pipe in the crawl space — each one takes its own temperature, and each one gets two margins: how many degrees before it condenses, and how many before it reaches the 80 % line where mould can grow. That second number is why "not condensing" is not the same as "fine". Both unit cultures. Celsius with grams per kilogram, or Fahrenheit with grains per pound. Air pressure is an input, because water mass runs inversely with it and a room at altitude is not a room at sea level. The arithmetic is in the app. Six anchors, from a dew point to an adiabatic mix. The formulas are named on the How it works screen — Magnus for saturation pressure, Stull for wet bulb, conservation of water and heat for mixing — together with six values checked against published figures, so you can hold the app against a psychrometric chart and see where it stands. Nothing leaves this device. No account, no server, no location. Languages: English, 한국어, 日本語, 繁體中文, Deutsch, Français, Español