R/psychrometric-graph-slope-rel-hum.R

In jinlee86/bems_analysisr_package: EDAS System R Package

#' Slope of relative humidity line
#'
#' Calculate slope of relative humidity line.
#' @param temp.1 Temperature of first point [degC].
#' @param temp.2 Temperature of second point [degC].
#' @param rel.hum Relative humidity line to find slope of [\%].
#' @family PsychrometricGraph
#' @return Returns the slope angle [deg].
#' @keywords internal
#' @examples
#' slope_rel_hum(15, 20, 80)
#' @author Christoffer Rasmussen

slope_rel_hum <- function(temp.1, temp.2, rel.hum) {
  
  x1 <- temp.1
  x2 <- temp.2
  y1 <- hum_ratio(rel.hum, temp.1)
  y2 <- hum_ratio(rel.hum, temp.2)
  
  angle <- atan((y2 - y1) * 1000 / (x2 - x1))
  
  return(angle * 180 / pi)
}