Function to calculate water vapour pressure (hPa) from temperature (°C) and relative humidity (%).
Water vapour pressure is the pressure exerted by water vapour in a gas.
Arguments
- Temp
Temperature (°Celsius)
- RH
Relative Humidity (0-100%)
- ...
Additional arguments to supply to
calcPws
Details
The water vapor pressure (P_w) is calculated using the following equation:
$$P_w=\frac{P_{ws}\left(Temp\right)\times RH}{100}$$
Where:
P_ws is the saturation vapor pressure using
calcPws.RH is the relative humidity in percent.
Temp is the temperature in degrees Celsius.
References
Wagner, W., & Pru\ß, A. (2002). The IAPWS formulation 1995 for the thermodynamic properties of ordinary water substance for general and scientific use. Journal of Physical and Chemical Reference Data, 31(2), 387-535.
Alduchov, O. A., and R. E. Eskridge, 1996: Improved Magnus' form approximation of saturation vapor pressure. J. Appl. Meteor., 35, 601-609.
Examples
calcPw(20, 50)
#> [1] 11.69597
# Calculate relative humidity at 50%RH
calcPw(20, 50) / calcPws(20) * 100
#> [1] 50
head(mydata) |> dplyr::mutate(Pw = calcPw(Temp, RH))
#> # A tibble: 6 × 6
#> Site Sensor Date Temp RH Pw
#> <chr> <chr> <dttm> <dbl> <dbl> <dbl>
#> 1 London Room 1 2024-01-01 00:00:00 21.8 36.8 9.62
#> 2 London Room 1 2024-01-01 00:15:00 21.8 36.7 9.59
#> 3 London Room 1 2024-01-01 00:29:59 21.8 36.6 9.56
#> 4 London Room 1 2024-01-01 00:44:59 21.7 36.6 9.51
#> 5 London Room 1 2024-01-01 00:59:59 21.7 36.5 9.48
#> 6 London Room 1 2024-01-01 01:14:59 21.7 36.2 9.40