QFF
The explanation given regarding QFF and QNH in my book is as follows:
The QFE reduced to mean sea level using the temperature at the station which is an isothermal lapse rate.
The QNH is the QFE reduced to mean sea level using the standard lapse rate of 1.98/1000 ft.QNH is only used by Pilots and ATC
It further states:
QFF is used by meteorologists and is the pressure recorded on synoptic charts.
My question is:
a)What do they mean by an isothermal lapse rate?
b)In altimetry we are taught to find the QNH from a given QFE by using 1 hpa=27ft then isnt the QNH reduced to sea level using the standard pressure lapse rate instead of 1.98/1000 ft ?
c)Why dont the meteorologists use the QNH?
Thanks.