abstract
| - Pressure varies smoothly from the Earth's surface to the top of the mesosphere. Although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. The following is a list of air pressures (as a fraction of one atmosphere) with the corresponding average altitudes. The table gives a rough idea of air pressure at various altitudes. Subscript textInsert non-formatted text here== Calculating variation with altitude == See also: Barometric formula There are two different equations for computing the average pressure at various height regimes below km (). Equation 1 is used when the value of standard temperature lapse rate is not equal to zero and equation 2 is used when standard temperature lapse rate equals zero. Equation 1: Equation 2: where = Static pressure (pascals, Pa) = Standard temperature (kelvin, K) = Standard temperature lapse rate (kelvin per meter, K/m) = Height above sea level (meters, m) = Height at bottom of layer b (meters; e.g., = 11,000 m) = Universal gas constant: 8.31432 Nm/(K·mol) = Standard gravity (9.80665 m/s2) = Molar mass of Earth's air (0.0289644 kg/mol) Or converted to Imperial units: where = Static pressure (inches of mercury, inHg) = Standard temperature ([[kelvin]s, K) = Standard temperature lapse rate (kelvin per foot, K/ft) = Height above sea level (feet, ft) = Height at bottom of layer b (feet; e.g., = 36,089 ft) = Universal gas constant; using feet, kelvin, and (SI) moles: 8.9494596×104 gft2/(mol·Ks2) = Standard gravity (32.17405 ft/s2) = Molar mass of Earth's air (0.0289644 kg/mol) The value of subscript b ranges from 0 to 6 in accordance with each of seven successive layers of the atmosphere shown in the table below. In these equations, g0, M and R* are each single-valued constants, while P, L, T, and h are multivalued constants in accordance with the table below. (Note that according to the convention in this equation, L0, the tropospheric lapse rate, is negative.) It should be noted that the values used for M, g0, and are in accordance with the U.S. Standard Atmosphere, 1976, and that the value for in particular does not agree with standard values for this constant. The reference value for Pb for b = 0 is the defined sea level value, P0 = 101325 pascals or 29.92126 inHg. Values of Pb of b = 1 through b = 6 are obtained from the application of the appropriate member of the pair equations 1 and 2 for the case when .:
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