HumidCalc 4+

The COVID-19 is more susceptible to infection when the humidity ratio is less than 6g/kg(42gr/lb), according to UMD.
Check the humidity with this app & prevent infection!

If you use this app, you can easily obtain "Temperature-humidity index(Discomfort Index)", "WBGT(Heat stroke index)", "Dew point temperature", etc., from weather information.
Furthermore, the app calculates the air condition from dry-bulb temperature(Td) and wet-bulb temperature(Tw) obtained by Assmann-Psychrometer, etc., and the app can also input atmospheric pressure.
The app can calculate 11 items and 13 indicators, and conversion to the Celsius temperature and SI units (or in the Fahrenheit temperature and Imperial and US customary measurement systems) also you can simply by switching of "Temperature Unit".
The items and indicators that this app can calculate are as follows.

- Dew Point Temperature
- Relative Humidity
- Humidity Ratio(Absolute Humidity)
Weight absolute humidity
Weight absolute humidity in the more smaller unit.
Volume absolute humidity
- Humidity Deficit
- Enthalpy
- Specific Volume
- Equilibrium Vapor Pressure
- Partial Pressure
- Boiling Point of Water
- WBGT(Estimated value)
- Discomfort Index[Temperature-humidity index]

(( Supplementary explanation about the WBGT(Estimated value) and the Discomfort index.

The calculation formula of the outdoor WBGT is "WBGT = 0.7 Tnw + 0.1 Td + 0.2 Tg", but since there is no entry a item Globe thermometer temperature(Tg) in the app, so estimation the Globe thermometer temperature(Tg) by Dry-bulb temperature(Td).
- Calculation formula : "Tg = 1.45 Td - 27.162 [Temperature unit: ℉]”
There is a very strong correlation between Globe thermometer temperature(Tg) and Dry-bulb temperature(Td).
[Statistical information on this correlation : The number of samples is 17376 and the coefficient of determination(R^2) when statistics are taken is 0.919]

For natural wet-bulb temperature(Tnw), convert the Wet-bulb temperature(Tw) obtained by measurement by the Assmann Psychrometer to the Wet-bulb temperature(Tw) measured in natural state, a use it as Natural wet-bulb temperature(Tnw).
The natural state here means that the wind speed at the time of measurement is 5 meters per second(16.4 feet per second) or less.
The algorithm of this conversion is very special, so we omit the explanation.

"Discomfort Index" is "Temperature-humidity index".
The calculation formula is "Discomfort Index[DI] = 0.4 × (Td + Tw) +15 [Temperature unit: ℉]". ))

If you want to get the current atmospheric pressure, the current dry-bulb temperature(Td) and the current wet-bulb temperature(Tw), tap the "Weather" information button. By the way, In iPhone6, etc., you can get the atmospheric pressure by pressing "MEAS" button.
You can choose conditions of the wet bulb is you can choose any one of the “Normal" or “Froze” (※ If you choose the “Froze”, setting is enabled in when if sub-zero in wet-bulb temperature(Tw) ).
Even if you enter the measurement value such as a non-draft type psychrometer(for example, "Augusto Psychrometer", etc.), just tap the button and the corresponding value can be displayed (※ the app is subject to use of a ventilation type psychrometer in terms of measurement accuracy).
The app can receive the calculated value of dry bulb temperature (Td) and wet bulb temperature (Tw) from the sister app “Calculator of Air”.
If you use this function, you can input "dew point temperature", "relative humidity", etc. (※ there is a need to start up the "Calculator of Air" first).
Input range is the temperature is -30 ℃ to 50 ℃ (-22 ° F to 122 ° F), the atmospheric pressure is 600 hPa to 2475 hPa(17.72 inHg to 73.09 inHg).

This app is using the OpenWeatherMap(CC BY-SA4.0).


- Disclaimer 1.
Please input and use the temperature range(0 ℃ to 40 ℃ / 32°F to 104°F ) according to common sense as much as possible. If you enter an extreme value correct calculation result may not appear.

- Disclaimer 2.
We are not liable for any damage caused by the use of this application does not bear all of the responsibility.