RHtoVPD {plantecophys}

Conversions between relative humidity, vapour pressure deficit and dewpoint

Description

A collection of functions to convert between relative humidity (RH) (%), vapour pressure deficit (VPD) (kPa), dew point temperature, and leaf- or air temperature-based VPD or RH. To convert from relative humidity to VPD, use the RHtoVPD function, use VPDtoRH for the other way around. The water vapor saturation pressure is calculated with esat. Use DewtoVPD to convert from dewpoint temperature to VPD. The functions VPDleafToAir and VPDairToLeaf convert VPD from a leaf temperature to an air-temperature basis and vice versa. The functions RHleafToAir a RHairToLeaf do the same for relative humidity.

Usage

RHtoVPD(RH, TdegC, Pa = 101)

VPDtoRH(VPD, TdegC, Pa = 101)

esat(TdegC, Pa = 101)

VPDtoDew(VPD, TdegC, Pa = 101)

DewtoVPD(Tdew, TdegC, Pa = 101)

VPDleafToAir(VPD, Tleaf, Tair, Pa = 101)

VPDairToLeaf(VPD, Tair, Tleaf, Pa = 101)

RHleafToAir(RH, Tleaf, Tair, Pa = 101)

RHairToLeaf(RH, Tair, Tleaf, Pa = 101)

Arguments

RH

Relative humidity (%)

TdegC

Temperature (degrees C) (either leaf or air)

Pa

Atmospheric pressure (kPa)

VPD

Vapour pressure deficit (kPa)

Tdew

Dewpoint temperature (degrees C)

Tleaf

Leaf temperature (degrees C)

Tair

Air temperature (degrees C)

Details

The function describing saturated vapor pressure with temperature is taken from Jones (1992). All other calculations follow directly from the standard definitions, for which Jones (1992) may also be consulted.

Author(s)

Remko Duursma

References

Jones, H.G. 1992. Plants and microclimate: a quantitative approach to environmental plant physiology. 2nd Edition., 2nd Edn. Cambridge University Press, Cambridge. 428 p.