Normal height

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Normal heights (symbol or ;

above sea level introduced by Mikhail Molodenskii
. The normal height of a point is computed as the quotient of a point's
reference ellipsoid
— to ; the procedure is thus recursive.)

Normal heights are thus dependent upon the

geodetic levelling. Normal gravity values are easier to compute compared to actual gravity, as one does not have to know the Earth's crust density. This is an advantage of normal heights compared to orthometric heights
.

The reference surface that normal heights are measured from is called the quasi-geoid (or quasigeoid), a representation of

geoid undulation
with respect to the reference ellipsoid:

finds an analogue in the so-called height anomaly, :

The maximum geoid–quasigeoid separation (GQS), , is on the order of 5 meters in the Himalayas.[1][2]

Alternatives to normal heights include orthometric heights (geoid-based) and dynamic heights.

See also

References