Monday, 26 November 2012

0 height

The height has several meanings, depending on the discussed area.

Metrology (measurement science):
The height is the vertical distance from a point (or assimilated to a point object) and a reference level specified. Equivalently, the dimension of an object taken in the vertical direction. See international system of units.
In altimetry and geography, the height is named "altitude" when it measures the altitude (h) of a land point from a reference level (which is usually a Datum or reference ellipsoid). Not to be confused with the lift (H) of a terrestrial point.


The height is a perpendicular line segment that passes through the vertex of a polygon, a cylinder or a pyramid to its base.
The height of a triangle is the derived right of a Summit and that is perpendicular to the opposite side. Example: In a triangle ABC, the height H following the Summit A is perpendicular to the side [BC].


In astronomy, the height is the angle that is referred to the horizontal direction; It is the complement of the zenith distance. The height and azimuth are the horizontal coordinate system.


The depth of water is the magnitude reached by the tide at a given time; It is determined by a calculation of tide. Added to the probe indicated on the chart, it allows to know the effective depth at this time (maps marine - Datum reference level - being of the seas).
The height of an object (reef, wreck...) covered by the tide is counted since the chart datum and specified on the map by an underlined digit.
the height of a bitter, a tag, home to a lighthouse or the deck of a bridge is shown on nautical charts from the level reached by the full 95 coefficient seas.

Air navigation

The height is the vertical distance from a point to the ground. Not to be confused with altitude or flight level.
The elevation is the vertical distance from a point to the level of the sea. Therefore, the height and the altitude are equal above the sea.
The flight level (or FL = Flight level) is an isobaric surface. It is equal to the altitude where atmospheric pressure is 1013 hPa at sea level and sea level temperature is 15 ° C. It is only in this condition and above the sea height = altitude = flight level.
These definitions are common to all those moving in the air, the long-haul flight to the parachutist.


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