Calculate Humidity Ratio

Function to calculate humidity ratio (g/kg) from temperature (°C) and relative humidity (%).

Humidity ratio is the mass of water vapor present in a given volume of air relative to the mass of dry air.

Function uses calcMR

Usage

calcHR(Temp, RH, P_atm = 1013.25, B = 621.9907)

Arguments

Temp

Temperature (°Celsius)

RH

Relative Humidity (0-100%)

P_atm

Atmospheric pressure = 1013.25 (hPa)

B

B = 621.9907 g/kg for air

Value

HR Humidity ratio (g/kg)

Details

The function uses the following steps:

1. Calculate the mixing ratio using the calcMR function.

2. Convert the mixing ratio to humidity ratio using the formula:

HR = MR / (1 + MR)

Where MR is the mixing ratio and HR is the humidity ratio.

Note: This function requires the calcMR function to be available in the environment.

See also

calcMR for calculating mixing ratio

calcAD for calculating air density

calcPw for calculating water vapour pressure

calcPws for calculating water vapour saturation pressure

Examples

calcHR(20, 50)
#> [1] 0.8789858

head(mydata) |> dplyr::mutate(HumidityRatio = calcHR(Temp, RH))
#> # A tibble: 6 × 6
#>   Site   Sensor Date                 Temp    RH HumidityRatio
#>   <chr>  <chr>  <dttm>              <dbl> <dbl>         <dbl>
#> 1 London Room 1 2024-01-01 00:00:00  21.8  36.8         0.856
#> 2 London Room 1 2024-01-01 00:15:00  21.8  36.7         0.856
#> 3 London Room 1 2024-01-01 00:29:59  21.8  36.6         0.856
#> 4 London Room 1 2024-01-01 00:44:59  21.7  36.6         0.855
#> 5 London Room 1 2024-01-01 00:59:59  21.7  36.5         0.855
#> 6 London Room 1 2024-01-01 01:14:59  21.7  36.2         0.853