# The Air Navigation (Noise Certification) Order 1990, Schedule 2


“An International Standard Atmosphere at sea level” means an atmosphere having the following characteristics—
(a) the air is a perfect dry gas;
(b) the physical constants are—
(i) sea level mean molecular weight:
M0 28.9644
(ii) sea level atmospheric pressure:
P0
= 1013.250 millibars
= 1.013250 × 105 newtons−2
(iii) sea level temperature:
t0 = 15°C
T0 = 288.15°K
(iv) sea level atmospheric density:
P0 = 1.2250 kg m−3
(v) temperature of the ice point:
Ti = 273.15°K
(vi) universal gas constant:
R = 8.31432 joules (°K)−1 mol−1

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Source: https://www.legislation.gov.uk/uksi/1990/1514/schedule/2 (the official version)
Page: https://openlegislation.uk/air-navigation-noise-certification-order-1990/schedule-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.