above datum height
21Geodesy — (pronEng|dʒiːˈɒdɪsi [OED] ), also called geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three dimensional time varying… …
22Altitude — For other uses, see Altitude (disambiguation). Not to be confused with Attitude. Altitude or height is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, and more). As a general definition, altitude… …
23Geographic coordinate system — Map of Earth showing lines of latitude (horizontally) and longitude (vertically), Eckert VI projection; large version (pdf, 3.12MB) …
24surveying — /seuhr vay ing/, n. 1. the science or scientific method of making surveys of land. 2. the occupation of one who makes land surveys. 3. the act of one who surveys: The surveying required nearly two days. [1425 75; late ME: act of examining… …
25Normalhöhennull — NHN height sign in the Harz mountains of Germany on the Brocken road Normalhöhennull ( standard elevation zero ) or NHN is a standard reference level, the equivalent of sea level, used in Germany to measure height. In geographical terms, NHN is… …
26Sea level — For the sea level change associated with the current episode of global warming, see current sea level rise. For other uses, see Sea level (disambiguation). This marker indicating the sea level is placed on the path from Jerusalem to the Dead Sea …
27Tide — This article is about tides in the Earth s oceans. For other uses, see Tide (disambiguation). Tidal redirects here. For other uses, see Tidal (disambiguation). High Tide redirects here. For other uses, see High Tide (disambiguation) …
28Storm surge — or tidal surge is an offshore rise of water associated with a low pressure weather system, typically a tropical cyclone. Storm surge is caused primarily by high winds pushing on the ocean s surface. The wind causes the water to pile up higher… …
29Geodetic system — For other uses, see Geodetic. Geodesy Fundamentals …
30Atmospheric pressure — Air pressure redirects here. For the pressure of air in other systems, see pressure. Atmospheric pressure is the force per unit area exerted against a surface by the weight of air above that surface in the Earth s atmosphere. In most… …
