EcoHydRology (version 0.3.7)

EvapHeat: Evaporative heat exchange between a surface and the surrounding air

Description

Evaporative heat exchange between a surface and the surrounding air; usually cooling [kJ m-2 d-1] this function is only intended for wet surfaces, i.e., it assumes the vapor density at the surface is the saturation vapor density

Usage

EvapHeat(surftemp, airtemp, relativehumidity, Tn, wind)

Arguments

surftemp

surface temperature [C]

airtemp

average dailiy air temperature [C]

relativehumidity

relative humidity [-]

Tn

minimum dailiy air temperature, assumed to be the dewpoint temperature [C]

wind

average daily windspeed [m/s]

Value

Examples

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function(surftemp,airtemp,relativehumidity,Tn,wind){
# evaporative heat exchange between a surface and the surrounding air; usually cooling [kJ m-2 d-1]
# this function is only intended for wet surfaces, i.e., it assumes the vapor density at the surface is the saturation vapor density

#surftemp: surface temperature [C]
#airtemp: average dailiy air temperature [C]
#relativehumidity: relative humidity [-]
#Tn: minimum dailiy air temperature, assumed to be the dewpoint temperature [C]
#wind: average daily windspeed [m/s]

#NOTE: this function will use the relative humidity to esimate air vapor density if the value passed is greater than zero (0)
# If the relative humidity is less than one, we will assume the minimum daily air temperature is approsimate the dew point temp.

windfunction<-5.3*(1+wind)

if(relativehumidity>0){airvapordensity<-relativehumidity*SatVaporDensity(airtemp)}
else{airvapordensity<-SatVaporDensity(Tn)}

surfacevapordensity<-SatVaporDensity(surftemp)

return(86400*windfunction*(surfacevapordensity-airvapordensity))
  }