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  2. Wind gradient - Wikipedia

    en.wikipedia.org/wiki/Wind_gradient

    It is the rate of increase of wind strength with unit increase in height above ground level. [ 5 ] [ 6 ] In metric units, it is often measured in units of meters per second of speed, per kilometer of height (m/s/km), which reduces inverse milliseconds (ms −1 ), a unit also used for shear rate .

  3. Scale height - Wikipedia

    en.wikipedia.org/wiki/Scale_height

    In atmospheric, earth, and planetary sciences, a scale height, usually denoted by the capital letter H, is a distance (vertical or radial) over which a physical quantity decreases by a factor of e (the base of natural logarithms, approximately 2.718).

  4. Dedicated outdoor air system - Wikipedia

    en.wikipedia.org/wiki/Dedicated_outdoor_air_system

    [5] [6] A DOAS system solves this problem by providing a dedicated supply of 100% outdoor air. Need for excess outdoor air flow and conditioning in VAV systems: When the multiple spaces equation of ASHRAE Standard 62.1-2004 is used, generally from 20-70% more outdoor air is required in an effort to assure proper room air distribution in all air ...

  5. Tree height measurement - Wikipedia

    en.wikipedia.org/wiki/Tree_height_measurement

    The height of the tree above eye level is [h1 = sin(a) x D1]. The same process is used to measure the height or extension of the base of the tree above or below eye level where D1 is the distance to the base of the tree and (b) is the angle to the base of the tree.

  6. Reference datum height - Wikipedia

    en.wikipedia.org/wiki/Reference_datum_height

    In aviation, reference datum height (RDH) is the height of a point, located above the intersection of the runway centre line and the threshold, through which the downward extended straight portion of the glide path passes. [1] It is usually found on the aerodrome instrument approach charts.

  7. Speed of sound - Wikipedia

    en.wikipedia.org/wiki/Speed_of_sound

    The dependence on frequency and pressure are normally insignificant in practical applications. In dry air, the speed of sound increases by about 0.1 m/s as the frequency rises from 10 Hz to 100 Hz. For audible frequencies above 100 Hz it is relatively constant. Standard values of the speed of sound are quoted in the limit of low frequencies ...

  8. Thermosphere - Wikipedia

    en.wikipedia.org/wiki/Thermosphere

    The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of 45 kilometres (28 mi) and causes the ozone layer.

  9. Humidity - Wikipedia

    en.wikipedia.org/wiki/Humidity

    At 100% relative humidity, the air is saturated and is at its dew point. In the absence of a foreign body on which droplets or crystals can nucleate, the relative humidity can exceed 100%, in which case the air is said to be supersaturated. Introduction of some particles or a surface to a body of air above 100% relative humidity will allow ...