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The temperature of the air near the surface of the Earth is measured at meteorological observatories and weather stations, usually using thermometers placed in a shelter such as a Stevenson screen—a standardized, well-ventilated, white-painted instrument shelter. The thermometers should be positioned 1.25–2 m above the ground.
at each geopotential altitude, where g is the standard acceleration of gravity, and R specific is the specific gas constant for dry air (287.0528J⋅kg −1 ⋅K −1). The solution is given by the barometric formula. Air density must be calculated in order to solve for the pressure, and is used in calculating dynamic pressure for moving vehicles.
Trees cannot grow at high altitude, because of cold temperature or lack of available moisture. [82]: 51 The lack of trees causes an ecotone, or boundary, that is obvious to observers. This boundary is known as the tree line. The highest-altitude plant species is a moss that grows at 6,480 m (21,260 ft) on Mount Everest. [83]
Density Altitude Computation Chart [1] The density altitude is the altitude relative to standard atmospheric conditions at which the air density would be equal to the indicated air density at the place of observation. In other words, the density altitude is the air density given as a height above mean sea level.
It is measured as the mean of all annual temperatures, with all temperatures below freezing and above 30 °C adjusted to 0 °C, [4] as most plants are dormant at these temperatures. Holdridge's system uses biotemperature first, rather than the temperate latitude bias of Merriam 's life zones, and does not primarily consider elevation directly.
Which Southern California native plants survived climate change and mass extinctions 13,000 years ago and still live today? La Brea Tar Pits researchers compiled a list.
Winds can be high throughout the year and are a major factor limiting plant growth near the upper limit of the subalpine zone (tree line). Wind limits vegetative growth chiefly in two ways: by physically battering plants, including blowing snow and ice, and by increasing evapotranspiration in an environment that is already water-stressed. [4]
A Palmer oak in Jurupa Valley is estimated to be 13,000 to 18,000 years old. The plant, which looks like a sprawling, dark green shrub, is now at the center of a development battle.