11-566: The Zeller Blauen (more rarely: Hochblauen ) is a mountain, 1,077.1 m above sea level (NHN) , in the southern Black Forest in Germany . It belongs to Zell im Wiesental in the Baden-Württemberg county of Lörrach . The mountain, with its steep slopes to the south, west and east, dominates the Wiese valley north of the town of Zell and towers above it by more than 600 metres. To
22-485: A 1788 Black Forest map at St. Blaise Abbey the mountain is annotated as "auf dem hohen Blauen" ("on the high Blauen"). In the 1846 atlas, Topographischen Atlas ueber das Grossherzogtum Baden , it is called "Hochblauen". This description is also common for the mountain of Blauen , twelve kilometres away to the west-northwest. Normalh%C3%B6hennull Normalhöhennull ( German pronunciation: [nɔʁmaːlˈhøːənˌnʊl] , "standard elevation zero") or NHN
33-517: Is a vertical datum used in Germany. In geographical terms, NHN is the reference plane for the normal height of a topographical eminence height above mean sea level used in the 1932 German Mean Height Reference System ( Deutsches Haupthöhennetz ). The plane is in the shape of a quasi- geoid . The reference height is a geodetic , fixed point on the New Church of St. Alexander at Wallenhorst in
44-728: Is called the height anomaly or quasi-geoid height. Since 1 January 2000 the whole of Germany has changed its height system over to normal heights based on the datum of the Amsterdam Ordnance Datum , known as the German Mean Height Reference System, DHHN92. At the same time, the new NHN is the basis of the United European Levelling Net (UELN), formerly known as the Reseau Européen Unifié de Nivellement or REUN , which standardises
55-676: The Amsterdam Ordnance Datum and transferred to the New Berlin Observatory in order to define the Normalhöhenpunkt 1879 . Normalnull has been defined as a level going through an imaginary point 37.000 m below Normalhöhenpunkt 1879 . When the New Berlin Observatory was demolished in 1912 the reference point was moved east to the village of Hoppegarten (now part of the town of Müncheberg , Brandenburg , Germany ). This cartography or mapping term article
66-533: The Amsterdam Datum). The elevations differed — depending on location — by 0.06 to 0.16 m. As a result of new measurements as part of the changeover, however, variations of 0.59 m ( Zugspitze ) have surfaced. Older relief maps often show heights above the old reference planes. Current maps by the federal survey authorities are based on NHN. At the beginning of 2013 most of the federal states (except Berlin, Thuringia and Saxony-Anhalt) had complete coverage by
77-523: The German state of Lower Saxony . The geopotential height of this point was calculated in 1986 as part of the United European Levelling Network (UELN), based on the Amsterdam Ordnance Datum . The NHN plane is a theoretical reference plane. It is derived by deducting normal heights from the normal plumb line . The difference between the resulting quasi-geoid and the reference ellipsoid
88-531: The height systems of the European countries. Heights in this system are given in meters above NHN or m (NHN) . The NHN was introduced because for heights above Normalnull the actual gravitational field of the Earth was not taken into account. As a result, there were changes in both the old West German normal orthometric heights (new methods of calculation) and the normal heights of East Germany (with respect to
99-532: The new digital topographic mapping at 1:25,000 scale (DTK). Not all the maps have appeared in print yet. On the DTK25 maps, NHN is used for elevations; however, on the DTK25-V scanned topographic maps Höhennull (HN) and Normalnull (NN) are still being used. In East Germany normal heights used to be referred to as heights above Höhennormal or HN . The 1958 Kronstadt Tide Gauge ( Kronstädter Pegel )
110-640: The north a ridge runs from the forested summit region of the Zeller Blauen, between the Kleines Wiesental in the west and the Wiesental in the east, to the Belchen 10 kilometres away. Along the southern flank of the Zeller Blauen are the remains of military earthworks . On the west mountainside, at an elevation of about 700 to 800 metres in the parish of Adelsberg , are the hamlets of Blauen and Oberblauen. In
121-575: Was used as the datum. The new NHN heights are typically 12–15 cm higher. The maximum deviations in the spirit level points of first order are between 7 and 16 cm. Normalnull Normalnull ("standard zero") or Normal-Null (short N. N. or NN ) is an outdated official vertical datum used in Germany. Elevations using this reference system were to be marked Meter über Normal-Null (“meters above standard zero”). Normalnull has been replaced by Normalhöhennull (NHN). In 1878 reference heights were taken from
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