science

Normalhöhennull

Normalhöhennull is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Normalhöhennull rather than just read about it. In short: Normalhöhennull (German pronunciation: [nɔʁmaːlˈhøːənˌnʊl], "standard elevation zero") or NHN 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).

Key takeaways

Normalhöhennull belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Normalhöhennull to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Normalhöhennull from memory before moving on to harder problems.

Reference excerpt

Normalhöhennull (German pronunciation: [nɔʁmaːlˈhøːənˌnʊl], "standard elevation zero") or NHN 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 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.

Definition

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 is called the height anomaly or quasi-geoid height.

Change-over from NN to NHN 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 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 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 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.

Old East German height system In East Germany normal heights used to be referred to as heights above Höhennormal or HN. The 1958 Kronstadt Tide Gauge (Kronstädter Pegel) 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.

References

External links Description of NHN system Archived 3 March 2016 at the Wayback Machine (in English) LVA NRW: DHHN 92 Archived 15 April 2008 at the Wayback Machine (in German) BKG: Height reference systems (in German)

Illustrations

Worked examples

Example 1 — a first encounter with Normalhöhennull

Start with the simplest possible case. Write down what Normalhöhennull claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Normalhöhennull before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Normalhöhennull ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Normalhöhennull

In research: Normalhöhennull appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Normalhöhennull in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Normalhöhennull is common in secondary-school and first-year university syllabi. It links to neighbouring topics Vertical datums, so understanding it makes those chapters shorter.
In everyday life: Look for Normalhöhennull outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Normalhöhennull in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Normalhöhennull means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Normalhöhennull out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Normalhöhennull in simple terms?

Why does Normalhöhennull matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Normalhöhennull?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Normalhöhennull.