Mean sea level in the context of "Above mean sea level"

Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level varies in different countries due to different reference points and historic measurement periods. Climate change and other forces can cause sea levels and elevations to vary over time.

The superlative, tallest mountain is often used when what is meant is highest mountain.

The height of a mountain is normally expressed as its altitude above mean sea level. This means Mount Everest is the highest mountain above sea level on earth. But it is not the tallest mountain, either on Earth or off it.

A contour line (also isoline, isopleth, isoquant or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional graph of the function ${\displaystyle f(x,y)}$ parallel to the ${\displaystyle (x,y)}$-plane. More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value.

In cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes. The contour interval of a contour map is the difference in elevation between successive contour lines.

Enontekiö (Finnish: [ˈenontekiø]; Northern Sami: Eanodat [ˈe̯anoðah(t)]; Swedish: Enontekis; Inari Sami: Iänudâh; Skolt Sami: Jeänõk) is a municipality in the Finnish part of Lapland with approximately 1,800 inhabitants. It is situated in the outermost northwest of the country and occupies a large and very sparsely populated area of about 8,400 square kilometres (3,200 sq mi) between the Swedish and Norwegian border. Finland's highest point, the Halti fell, with a height of 1,324 metres (4,344 ft) above the mean sea level, is situated in the north of Enontekiö. The municipality shares borders with regions of Sweden and Norway that encompass the Scandinavian Mountains. The administrative centre of Enontekiö is the village of Hetta. About one fifth of the community's population are Sami people. Enontekiö's main industries are tourism and reindeer husbandry.

Vertical position or vertical location is a position along a vertical direction (the plumb line direction) above or below a given vertical datum (a reference level surface, such as mean sea level).Vertical distance or vertical separation is the distance between two vertical positions.Many vertical coordinates exist for expressing vertical position: depth, height, altitude, elevation, etc.Points lying on an equigeopotential surface are said to be on the same vertical level, as in a water level.A function with domain along the vertical line is called a vertical distribution or vertical profile.

The orthometric height (symbol H) is the vertical distance along the plumb line from a point of interest to a reference surface known as the geoid, the vertical datum that approximates mean sea level. Orthometric height is one of the scientific formalizations of a layman's "height above sea level", along with other types of heights in Geodesy.

In the US, the current NAVD88 datum is tied to a defined elevation at one point rather than to any location's exact mean sea level. Orthometric heights are usually used in the US for engineering work, although dynamic height may be chosen for large-scale hydrological purposes. Heights for measured points are shown on National Geodetic Survey data sheets, data that was gathered over many decades by precise spirit leveling over thousands of miles.

Geopotential height, also known as geopotential altitude or geopotential elevation, is a vertical coordinate (with dimension of length) representing the work involved in lifting one unit of mass over one unit of length through a hypothetical space in which the acceleration of gravity is assumed constant. Geopotential heights are referenced to Earth's mean sea level, taking its best-fitting equigeopotential as a reference surface or vertical datum.In SI units, a geopotential height difference of one meter implies the vertical transport of a parcel of one kilogram; adopting the standard gravity value (9.80665 m/s), it corresponds to a constant work or potential energy difference of 9.80665 joules.

Geopotential height differs from geometric height (as given by a tape measure) because Earth's gravity is not constant, varying markedly with altitude and latitude; thus, a 1-m geopotential height difference implies a different vertical distance in physical space: "the unit-mass must be lifted higher at the equator than at the pole, if the same amount of work is to be performed".It is a useful concept in meteorology, climatology, and oceanography; it also remains a historical convention in aeronautics as the altitude used for calibration of aircraft barometric altimeters.

A chart datum is the water surface serving as origin (or coordinate surface) of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. Common chart datums are lowest astronomical tide (LAT) and mean lower low water (MLLW). In non-tidal areas, e.g., the Baltic Sea, mean sea level (MSL) is used.

In geophysics, the free-air gravity anomaly, often simply called the free-air anomaly, is the measured gravity anomaly after a free-air correction is applied to account for the elevation at which a measurement is made. It does so by adjusting these measurements of gravity to what would have been measured at a reference level, which is commonly taken as mean sea level or the geoid.