INTERNATIONAL STANDARD ISO2533-1975 (E) Standard Atmosphere (identical with the ICAO and WMO Standard Atmospheres from --2 to 32 km) 1 SCOPEAND FIELD OFAPPLICATION T。 thermodynamic ice-point temperature, at mean sea level; This International Standard specifies the characteristics of an Iso Standard Atmosphere and is intended for use in standard thermodynamic air temperature at calcuiations and design of flying vehicles, to present the test mean sea level; results of flying vehicles and their components under t。 Celsius ice-point temperature at mean sea level; identical conditions, and to allow unification in the field of development and calibration of instruments. Its use is also standard Celsius air temperature at mean sea tn recommended in the processing of data from geophysical level; and meteorological observations. Cp adiabatic index, the ratio of the specific heat of K air at constant pressure to its specific heat at constant volume; standard air density; 2 BASIC PRINCIPLES AND CALCULATION FOR. Pn MULAE effective collision diameter of an air molecule; taken as constant with altitude. 2.1 Primary constants and characteristics The tables of the iso Standard Atmosphere have been TABLE 1 --- Main constants and characteristics adopted for the moisture and dust and based on conventional initial values calculation of the ISO Standard Atmosphere of temperature, pressure and density of the air for mean sea Symbol level. The foilowing constants and characteristics are used Value Unit of measurement for calculations and their numerical vaiues are given in 9n 9,806 65 m·s-2 table 1 : M 28,964 420 .kg kmol-1 -- standard acceleration of free fall. It conforms 9n NA 602,257×1024 kmot-1 with latitude =45°32'33" using Lambert's equation of the acceleration of free fall as a Pn 101,325×103 Pa function of latitude [5] : 1,013250×103 mbar 760 9p = 9,806 16 (1 - 0,002 637 3 cos 2 mmHg + 0,000 005 9 cos? 2) R* 8 314,32 J. K-1 . kmol-1 or M - air molar mass at sea level, as obtained from the kg - m2 . s-2. K-1 . kmol-1 perfect gas law (2) when introducing the 287,052 87 R J·K-1. kg-1 adopted values Pn, Pn, T,, R* (see tabie 1); or NA m2. k-1.s-2 - Avogadro constant, based on the value of the nuclide 12c, atomic mass = 12,000, as adopted s 110,4 K in 1961 by the Conference of the International T。 273,15 Union of Pure and Applied Chemistry as the Tn 288,15 K basic atomic mass unity; to 0,00 °c Pn - standard air pressure; tn 15,00 °c R* - universal gas constant; βs 1,458 ×10-6 kg+m-1 . s-1 . -1/2 R 1,4 K dimensionless - specific gas constant; 1,225 Sandβ, -- Sutheriand's empirical coefficients Pn kg -m-3 inthe 0,365 × 10-9 a m equation for dynamic viscosity; 1 ISO2533-1975 (E) By dividing the geopotential @ by the standard acceleration 2.2 The equation of the static atmosphere and the perfect of free fall gn, one obtains the value of a length dimension gas law which, symbolized as H, wil be : h Being static with respect to the earth, the atmosphere is H= g(h)dh .. (6) subject to gravity. The conditions of air static equilibrium 9n gn.lo are determined by the equation of the static atmosphere which relates air pressure p, density p, acceleration of free Expressed in metres, the vaiue H is numerically equal to the fail g and altitude h as follows : geopotential altitude, which in meteorology is measured in so-called standard geopotential metres1); hence, this value ... (1) - dp = pgdh will be called geopotential altitude. The mean sea level is taken as a reference for readings for both geopotential and The perfect gas law relates air pressure to density and geometrical altitudes. temperature as follows : From equation (6) it can be seen that, in order to relate geopotential and geometric altitudes, it is necessary first to pR*T find a relation between acceleration of free fall g and p= M geometric altitude h. It is known that gravity is a vectorial summation of the At the altitudes considered in this International Standard, gravitational attr