IDPmisc (version 1.1.20)

humidity: 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)

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 (\(-65^\circ\textnormal{C} <= T <= 0^\circ\textnormal{C}\)).

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.

Author

Rene Locher

Details

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

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)