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  2. Stand density index - Wikipedia

    en.wikipedia.org/wiki/Stand_Density_Index

    This equation can be rewritten as: log 10 SDI = log 10 N + 1.605 log 10 D - 1.605 The above equation is an expression for computing the stand density index from the number of trees per acre and the diameter of the tree of average basal area. Assume that a stand with basal area of 150 square feet (14 m 2) and 400 trees per acre is measured. The ...

  3. Tortuosity - Wikipedia

    en.wikipedia.org/wiki/Tortuosity

    Dividing the result by length of curve or chord has also been tried. In 2002 several Italian scientists [4] proposed one more method. At first, the curve is divided into several (N) parts with constant sign of curvature (using hysteresis to decrease sensitivity to noise). Then the arc-chord ratio for each part is found and the tortuosity is ...

  4. Hypsometry - Wikipedia

    en.wikipedia.org/wiki/Hypsometry

    The curve can also be shown in non-dimensional or standardized form by scaling elevation and area by the maximum values. The non-dimensional hypsometric curve provides a hydrologist or a geomorphologist with a way to assess the similarity of watersheds — and is one of several characteristics used for doing so. The hypsometric integral is a ...

  5. Curved space - Wikipedia

    en.wikipedia.org/wiki/Curved_space

    The surface of a sphere can be completely described by two dimensions, since no matter how rough the surface may appear to be, it is still only a surface, which is the two-dimensional outside border of a volume. Even the surface of the Earth, which is fractal in complexity, is still only a two-dimensional boundary along the outside of a volume. [3]

  6. Geodesic - Wikipedia

    en.wikipedia.org/wiki/Geodesic

    Klein quartic with 28 geodesics (marked by 7 colors and 4 patterns). In geometry, a geodesic (/ ˌ dʒ iː. ə ˈ d ɛ s ɪ k,-oʊ-,-ˈ d iː s ɪ k,-z ɪ k /) [1] [2] is a curve representing in some sense the locally [a] shortest [b] path between two points in a surface, or more generally in a Riemannian manifold.

  7. International Standard Atmosphere - Wikipedia

    en.wikipedia.org/wiki/International_Standard...

    The COSPAR International Reference Atmosphere (CIRA) 2012 and the ISO 14222 Earth Atmosphere Density standard both recommend NRLMSISE-00 for composition uses. JB2008 is a newer model of the Earth's atmosphere from 120 km to 2000 km, developed by the US Air Force Space Command and Space Environment Technologies taking into account realistic ...

  8. Gravity of Earth - Wikipedia

    en.wikipedia.org/wiki/Gravity_of_Earth

    The density at the center is the same as in the PREM, but the surface density is chosen so that the mass of the sphere equals the mass of the real Earth. See also: Shell theorem An approximate value for gravity at a distance r from the center of the Earth can be obtained by assuming that the Earth's density is spherically symmetric.

  9. Earth mass - Wikipedia

    en.wikipedia.org/wiki/Earth_mass

    An Earth mass (denoted as M 🜨, M ♁ or M E, where 🜨 and ♁ are the astronomical symbols for Earth), is a unit of mass equal to the mass of the planet Earth. The current best estimate for the mass of Earth is M 🜨 = 5.9722 × 10 24 kg, with a relative uncertainty of 10 −4. [2] It is equivalent to an average density of 5515 kg/m 3.