bigleaf (version 0.7.0)

wetbulb.temp: Wet-Bulb Temperature

Description

calculates the wet bulb temperature, i.e. the temperature that the air would have if it was saturated.

Usage

wetbulb.temp(Tair, pressure, VPD, accuracy = 0.001,
  Esat.formula = c("Sonntag_1990", "Alduchov_1996", "Allen_1998"),
  constants = bigleaf.constants())

Arguments

Tair

Air temperature (deg C)

pressure

Atmospheric pressure (kPa)

VPD

Vapor pressure deficit (kPa)

accuracy

Accuracy of the result (deg C)

Esat.formula

Optional: formula to be used for the calculation of esat and the slope of esat. One of "Sonntag_1990" (Default), "Alduchov_1996", or "Allen_1998". See Esat.slope.

constants

cp - specific heat of air for constant pressure (J K-1 kg-1) eps - ratio of the molecular weight of water vapor to dry air (-) Pa2kPa - conversion pascal (Pa) to kilopascal (kPa)

Value

Tw -

wet-bulb temperature (degC)

Details

Wet-bulb temperature (Tw) is calculated from the following expression:

$$e = Esat(Tw) - gamma* (Tair - Tw)$$

The equation is solved for Tw using optimize. Actual vapor pressure e (kPa) is calculated from VPD using the function VPD.to.e. The psychrometric constant gamma (kPa K-1) is calculated from psychrometric.constant.

References

Monteith J.L., Unsworth M.H., 2008: Principles of Environmental Physics. 3rd edition. Academic Press, London.

Examples

# NOT RUN {
wetbulb.temp(Tair=c(20,25),pressure=100,VPD=c(1,1.6))             
       
# }