QNH - Temperature Correction?
It has always been my understanding, that the QNH is the barometric pressure, when set on a subscale of an aircraft altimeter, will give the aircraft's height above mean sea level.
There are a large number of Met Reporting Stations, all feeding their data into the Met Bureau, who from the readings given, determine the "Area QNH". Aerodrome QNH is either given by ATC, or the Terminal Area Forecast.
The only temperature correction that I am aware of, is to apply the temperature when determining "Density Altitude", for take off and landing distance calculations.
On first contact with Tower or Approach, the QNH and Temperature are given, either by ATC, or on an ATIS broadcast.
Years ago, I saw a fully laden B707 waiting for one degree drop in Temperature, in order to achieve take off on the runway distance available.
"QNH is QNH, and Temperature is Temperature". Combined, calculation of Density Altitude is done.
What do you think.