Altitude Reference Libraries
A radar altimeter measures altitude above the terrain beneath an aircraft as opposed to a barometric altimeter which provides the distance above a pre-determined datum, usually sea level. Radar is the underpinning principle of the system. Radio waves that are reflected back from the ground are timed in order to calculate speed, distance, and time which are related to the each other and can be...
- A coin originally worth six pennies Scots, and later three; held equivalent to an English halfpenny.
- (in plural) Money; cash.