# Te: Operative temperature estimate. In Thermimage: Thermal Image Analysis

## Description

Operative temperature (degrees Celsius) is a measure of the effective temperature an object/animal will be given a specific radiative and convective environment. Basal heat production and evaporative heat loss are assumed to balance each other out.

## Usage

 ```1 2``` ```Te(Ts=30, Ta=25, Tg=NULL, RH=0.5, E=0.96, rho=0.1, cloud=0, SE=0, V=1, L=0.1, c=NULL, n=NULL, a=NULL, b=NULL, m=NULL, type="forced", shape="hcylinder") ```

## Arguments

 `Ts` Surface temperature (degrees Celsius). Default value is 30. Used in free convection calculation. `Ta` Air temperature (degrees Celsius). Default value is 20. Used to estimate ground temperature if Tg is unavailable. `Tg` Ground temperature (degrees Celsius). Default value is NULL, but a measured Tg can be substituted or estimated with other functions. `RH` Relative humidity (fraction 0 to 1). Default value is 0.5. Used in call to Ld() to determine incoming radiation. `E` Emissivity (fraction 0 to 1) of the object absorbing longwave radiation. According to Kirschoff's law, emissivity = absorptivity. Absorptivity is multiplied by the average of the incoming longwave radiation to estimate absorbed radiation. `rho` Reflectivity (fraction 0 to 1) of the object absorbing solar radiation. Used to modify absorbed solar energy. Default is 0.1. `cloud` Fractional cloud cover (fraction from 0 to 1). Used in call to Ld() to determine incoming radiation. Default is 0. `SE` Solar energy (W/m2), usually measured. Default is 100. `V` Air velocity (m/s). Default value is 1. `L` Characteristic dimension (m) of object. Usually the vertical dimension (i.e. height). Default value is 1. `c` coefficient used in forced convection (see Blaxter, 1986, default value is 0.24) `n` coefficient used in forced convection (see Blaxter, 1986, default value is 0.6) `a` coefficient used in free convection (see Gates, 2003, default value is 1) `b` coefficient used in free convection (0.58 upright cylinder, 0.48 flat cylinder, default value is 0.58) `m` coefficient used in free convection (0.25 laminar flow, default value is 0.25) `type` "forced" or "free" - to calculate convection coefficient for either forced or free convection. Default value is "forced" `shape` "sphere", "hplate", "vplate", "hcylinder", "vcylinder" to denote shape and orientation. h=horizontal, v=vertical. Default shape is "hcylinder"

## Details

Estimates operative temperature according to calculations in Gates (2003) and Angiletta ()

## Author(s)

Glenn J Tattersall

## References

Angiletta, M. J. 2009. Thermal Adaptation: A Theoretical and Empirical Synthesis. Oxford University Press, Oxford, UK, 304 pp. Gates, D.M. 2003. Biophysical Ecology. Courier Corporation, 656 pp.

`qabs` `hconv`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16``` ```# Example Ts<-40 Ta<-30 SE<-seq(0,1500,100) Toperative<-NULL for(rho in seq(0, 1, 0.1)){ temp<-Te(Ts=Ts, Ta=Ta, Tg=NULL, RH=0.5, E=0.96, rho=rho, cloud=1, SE=SE, V=0.1, L=0.1, type="free", shape="hcylinder") Toperative<-cbind(Toperative, temp) } Toperative<-data.frame(SE=seq(0,1500,100), Toperative) colnames(Toperative)<-c("SE", seq(0,1,0.1)) matplot(Toperative\$SE, Toperative[,-1], ylim=c(30, 50), type="l", xlim=c(0,1000), ylab="Operative Temperature (C)", xlab="Solar Radiation (W/m2)", lty=1, col=flirpal[rev(seq(1,380,35))]) ```