Height is measure of verticaldistance, either vertical extent (how "tall" something or someone is) orvertical position (how "high" a point is). For an example of vertical extent, "This basketball player is 7 foot 1 inches in height." For an example of vertical position, "The height of an airplane in-flight is about 10,000 meters."
When the term is used to describe vertical position (of, e.g., an airplane) fromsea level, height is more often calledaltitude.[1]Furthermore, if the point is attached to the Earth (e.g., a mountain peak), then altitude (height above sea level) is calledelevation.[2]
In a two-dimensionalCartesian space, height is measured along the vertical axis (y) between a specific point and another that does not have the samey-value. If both points happen to have the samey-value, then their relative height is zero. In the case ofthree-dimensional space, height is measured along the verticalz axis, describing a distance from (or "above") thex-y plane.
The English-language wordhigh is derived fromOld Englishhēah, ultimately from Proto-Germanic *xauxa-z, from aPIE base*keuk-. The derived nounheight, also the obsolete formsheighth andhighth, is from Old Englishhíehþo, laterhéahþu, as it were from Proto-Germanic*xaux-iþa.
In elementary models of space, height may indicate the thirddimension, the other two beinglength andwidth. Height is normal to the plane formed by the length and width.
Height is also used as a name for some more abstract definitions. These include:
Theheight or altitude of a triangle, which is the length from a vertex of a triangle to the line formed by the opposite side;
Theheight of a pyramid, which is the smallest distance from the apex to the base;
A measurement in acircular segment of the distance from the midpoint of the arc of the circular segment to the midpoint of the line joining the endpoints of the arc (see diagram incircular segment);
In arooted tree, theheight of a vertex is the length of the longest downward path to a leaf from that vertex;
Although height is normally relative to a plane of reference, most measurements of height in the physical world are based upon a zero surface, known assea level. Both altitude and elevation, two synonyms for height, are usually defined as the position of a point above the mean sea level. One can extend the sea-level surface under the continents: naively, one can imagine a lot of narrow canals through the continents. In practice, the sea level under a continent has to be computed from gravity measurements, and slightly different computational methods exist; seeGeodesy, heights.
In addition to vertical position, the vertical extent of geographic landmarks can be defined in terms oftopographic prominence. For example, the highest mountain (by elevation in reference to sea level) belongs toMount Everest, located on the border ofNepal andTibet, China; however thetallest mountain, by measurement of apex to base, isMauna Kea inHawaii, United States.
Geodesists formalize mean sea level (MSL) by means of thegeoid, the equipotential surface that best fits MSL. Then various types of height (normal, dynamic, orthometric, etc.) can be defined, based on the assumption of density of topographic masses necessary in the continuation of MSL under the continents.
In aviation terminology, the termsheight,altitude, andelevation are not synonyms. Usually, the altitude of an aircraft is measured from sea level, while its height is measured from ground level. Elevation is also measured from sea level, but is most often regarded as a property of the ground. Thus, elevation plus height can equal altitude, but the termaltitude has several meanings in aviation.
Human height is one of the areas of study withinanthropometry. While environmental factors have some effect on variations in human height, these influences are insufficient to account for all differences between populations, suggesting thatgenetic factors are important for explaining variations between human populations.[3]
In their research, Baten, Stegl and van der Eng came to the conclusion that a change in the average height is a sign for a change in the economic development. With broad data of Indonesia, the researchers state that several incidents in the history of the country has led not only to a change in the economy but also to a change in the population's average height.[4]
^Petersen, James F.; Sack, Dorothy; Gabler, Robert E. (4 February 2016).Physical Geography. Cengage Learning. p. 113.ISBN978-1-305-65264-4.Note that altitude usually refers to a height in the air (above sea level) and elevation refers to height on the surface [of the Earth] above (or below) sea level.
