Normalhöhennull

Normalhöhennull (NHN) is a standard reference system used in Germany to measure the altitude or elevation of geographical features. It is a vertical datum that represents the mean sea level in the North Sea, specifically at the Amsterdam Ordnance Datum.

Overview

The term "Normalhöhennull" is German and translates to "standard height zero". It is often abbreviated as NHN. The NHN system replaced the Normalnull (NN) system, which was based on the mean sea level at Astronomical Observatory of Berlin-Dahlem. The change was made to align Germany's altitude measurements with those of other European countries.

Measurement

The NHN is determined by the Earth's gravitational force, which is measured using geodetic and gravimetric methods. These measurements are then used to calculate the geoid, a theoretical surface that represents mean sea level. The difference between the geoid and the actual surface of the Earth is the NHN height.

Applications

The NHN is used in a variety of fields, including cartography, geography, civil engineering, and environmental planning. It is also used in navigation, particularly in the creation of topographic maps and nautical charts.

See also

• Geodesy
• Geoid
• Altitude
• Elevation