ankurdesai
commented
9 years ago It should be, but for atmospheric sea level surface pressure range, the effect is relatively small. see: http://www.humidity-calculator.com/index.php http://www.humidity-calculator.com/index.php and: http://www.humidity-calculator.com/index.php http://www.humidity-calculator.com/index.php
It should essentially be the reverse of qcshum in metutils which goes from SH to RH. Use Clausius-Clapeyron approximation to get saturation vapor pressure (Es in Pa) from Tair Multiple Rh by Es to get vapor pressure (E) in Pa Convert E to SH (or AH) in kg/kg based on air pressure (in Pa)
rh2qair looks like an approximation. A good test would be qair2rh(rh2qair(R,T) should return R within approximation
Ankur R Desai, Associate Professor University of Wisconsin - Madison, Atmospheric and Oceanic Sciences http://flux.aos.wisc.edu http://flux.aos.wisc.edu/ desai@aos.wisc.edu mailto:desai@aos.wisc.edu O: +1-608-520-0305 / M: +1-608-218-4208
On Jun 27, 2015, at 3:41 AM, fabeuw notifications@github.com wrote:
@mdietze https://github.com/mdietze In this formula to convert RH to SH pressure is not included, why? Isn't RH dependent on pressure?
' converts relative humidity to specific humidity
' @title https://github.com/title RH to SH
' @param https://github.com/param rh relative humidity (proportion, not %)
' @param https://github.com/param T absolute temperature (Kelvin)
' @export https://github.com/export
' @author https://github.com/author Mike Dietze
' @aliases https://github.com/aliases rh2rv
rh2qair <- function(rh, T){ qair <- rh * 2.541e6 * exp(-5415.0 / T) * 18/29 return(qair) }
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mdietze
fabeit
dlebauer
ashiklom
github-actions[bot]
@mdietze In this formula to convert RH to SH pressure is not included, why? Isn't RH dependent on pressure?
' converts relative humidity to specific humidity
' @title RH to SH
' @param rh relative humidity (proportion, not %)
' @param T absolute temperature (Kelvin)
' @export
' @author Mike Dietze
' @aliases rh2rv
rh2qair <- function(rh, T){ qair <- rh * 2.541e6 * exp(-5415.0 / T) * 18/29 return(qair) }