R: Converting Humidity Measures into Each Other

humidity {IDPmisc} | R Documentation

## Converting Humidity Measures into Each Other

### Description

Converting dew point (of water in air) into vapor pressure or relative humidity and vice versa.

### Usage

    hr(T, Td, warn = TRUE)
    pw(Td, warn = TRUE)
    pw.ai(Td, warn = TRUE)
    pw.aw(Td, warn = TRUE)
    Td(pw = NULL, T = NULL, hr = NULL, warn = TRUE)
    Td.aw(pw = NULL, T = NULL, hr = NULL, warn = TRUE)
    Tf.ai(pw = NULL, T = NULL, hr = NULL, warn = TRUE)

### Arguments

`hr` | Relative humidity in [\textnormal{\%}].
`T` | Temperature of air in [^\circ \textnormal{C}].
`Td` | Dew point of air in [^\circ \textnormal{C}].
`pw` | Saturation vapour pressure in [\textnormal{hPa}].
`warn` | When `TRUE` and arguments are out of range, a warning is thrown.

### Details

All vapour pressures correspond to pure water vapour and are not adjusted to water vapour in air.

### Value

`hr` transforms dew point above ice / water at a certain temperature into relative humidity (-65^\circ\textnormal{C} <= T <= 60^\circ\textnormal{C}).
`pw` transforms dew point into saturation vapour pressure above ice (-65^\circ\textnormal{C} <= T <= 0^\circ\textnormal{C}) and above water (0^\circ\textnormal{C} < T <= 60^\circ\textnormal{C}) respectively.
`pw.ai` transforms dew point into saturation vapour pressure above ice (-65^\circ\textnormal{C} <= T <= 0^\circ\textnormal{C}).
`pw.aw` transforms dew point into saturation vapour pressure above liquid water (-45^\circ\textnormal{C} <= T <= 60^\circ\textnormal{C}).
`Td` transforms vapour pressure or relative humidity and temperature into frost point above ice (-65^\circ\textnormal{C} <= T <= 0^\circ\textnormal{C}) and dew point above water (0^\circ\textnormal{C} < T <= 60^\circ\textnormal{C}) respectively.
`Td.aw` transforms vapour pressure or relative humidity and temperature into dew point above water (-45^\circ\textnormal{C} <= T <= 60^\circ\textnormal{C}).
`Tf.ai` transforms vapour pressure or relative humidity and temperature into frost point above ice (-65^\circ\textnormal{C} <= T <= 0^\circ\textnormal{C}).

### Author(s)

Rene Locher

### References

Guide to Meteorological Instruments and Methods of Observation, WMO, WMO-No. 8, Seventh edition, 2008, updated 2010, 1.4-29 Annex 4.B

### Examples

     pw(Td = c(-65, -45, 0, 30, 60))
     Td(pw = pw(c(-20, 0, 20)))

     hr(T = c(20, 30, 40), Td = c(0, 20, 30))
     ## [1] 26.20257 55.09561 57.46519

     hr(T = seq(0, 60, 5), Td = 0)

[Package IDPmisc version 1.1.20 Index]