Calculate relative humidity

Calculate relative humidity \(RH\) (%) from actual and saturation values of vapor pressure, mixing ratio, specific humidity, or absolute humidity.

Usage

cal_relative_humidity(e, es)

Arguments

e

Numeric. Actual humidity value. Can be vapor pressure, mixing ratio, specific humidity, or absolute humidity.

es

Numeric. Saturation value corresponding to e, using the same unit and type.

Value

Numeric value of relative humidity (%).

Details

Relative humidity \(RH\) (%) quantifies the air’s proximity to saturation. It is calculated using the formula:

$$RH = \frac{e}{e_s} \cdot 100 \approx \frac{w}{w_s} \cdot 100 \approx \frac{q}{q_s} \cdot 100 \approx \frac{\rho_v}{\rho_{vs}} \cdot 100$$

where \(e, w, q, \rho_v\) is the actual value and \(e_s, w_s, q_s, \rho_{vs}\) is the corresponding saturation value of vapor pressure, mixing ratio, specific humidity, or absolute humidity.

References

Davis, Robert E., Glenn R. McGregor, and Kyle B. Enfield. “Humidity: A Review and Primer on Atmospheric Moisture and Human Health.” Environmental Research 144 (January 2016): 106–16. https://doi.org/10.1016/j.envres.2015.10.014.

See also

cal_saturation_vapor_pressure(), cal_mixing_ratio(), cal_specific_humidity(), cal_absolute_humidity(), weathermetrics::dewpoint.to.humidity()

Examples

# Using vapor pressure (in hPa)
cal_relative_humidity(e = 10, es = 23.4)
#> [1] 42.73504

# Using specific humidity (in g/kg)
cal_relative_humidity(e = 7, es = 14)
#> [1] 50