Look up: qnh

1. 
   QNH
   abbreviation: Altimeter setting which provides height above mean sea level
   Found on http://www.apscharts.com/abbrev.html
   
   
2. 
   QNH
   Regional pressure setting corrected at sea level - adjusting an altimeter to this setting should indicate height above sea level. (nb - to find out height above ground level you can use the map and work out a spot height or an global positioning system (a machine that uses satellites to measure position, altitude and speed travelling as well as grid references) and take that away from the height above sea level which is considered to start at zero feet.
   Found on http://www.bized.co.uk/virtual/cb/glossa
   
   
3. 
   QNH
   `QNH` is a Q code. It is a pressure setting used by pilots, air traffic control (ATC) and low frequency weather beacons to refer to the barometric altimeter setting which will cause the altimeter to read altitude above mean sea level within a certain defined region. This region may be fairly widespread, or apply only to the airfield for which the QNH was given. An airfield QNH will cause the altimeter to read field elevation on landing irrespecti...
   Found on http://en.wikipedia.org/wiki/QNH