Calculate temperature-humidity index

Calculate temperature-humidity index \(THI\) (°F) from air temperature \(T\) (°F) and wet-bulb temperature \(T_w\) (°F).

Usage

cal_temperature_humidity_index(t, tw, t_unit)

Arguments

t, tw

Numeric. Air temperature and wet-bulb temperature in degree Celsius (°C), degree Fahrenheit (°F), or Kelvin (K).

t_unit

Character string. Unit of the temperature values. Must be one of "celsius", "fahrenheit", or "kelvin".

Value

Numeric value of temperature-humidity index in degree Fahrenheit (°F).

Details

Temperature-humidity index \(THI\) (°F), or “discomfort index”, is an index used to assess human comfort. It is calculated using the formula:

$$THI = 0.4 \cdot (T + T_w) + 15$$

where \(T\) is the air temperature and \(T_w\) is the wet-bulb temperature, in degrees Fahrenheit (°F).

The temperature input is converted to degree Fahrenheit (°F) based on the provided t_unit before calculation.

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.

Thom, E. C. “The Discomfort Index.” Weatherwise 12, no. 2 (April 1959): 57–61. https://doi.org/10.1080/00431672.1959.9926960.

See also

psychrolib::GetTWetBulbFromHumRatio(), psychrolib::GetTWetBulbFromRelHum(), psychrolib::GetTWetBulbFromTDewPoint()

Examples

cal_temperature_humidity_index(t = 68, tw = 52.34, t_unit = 'fahrenheit')
#> [1] 63.136
cal_temperature_humidity_index(t = 20, tw = 11.3, t_unit = 'celsius')
#> [1] 63.136