ISO 2533:1975

Overview

ISO 2533:1975 - Standard Atmosphere defines a reference atmospheric model and tabulated properties for a standardized “ISO Standard Atmosphere.” First published in 1975 (corrected/reprinted 1978), it provides a unified set of atmospheric characteristics (temperature, pressure, density and derived properties) for use in design, testing and data processing. The document is identical with the ICAO and WMO Standard Atmospheres in the range −2 km to 32 km and extends tabulated values (geopotential and geometric altitudes) from −2 000 m up to 50 000 m, with an interim extension to 80 000 m.

Key topics

• Reference constants and sea‑level conditions: standard gravity, universal and specific gas constants, molar mass and adopted sea‑level temperature/pressure/density.
• Altitude systems: relationship and conversion between geopotential and geometric altitudes; definition of geopotential metres.
• Temperature profile: layerwise linear temperature variation (lapse rates), tropopause/stratopause/mesopause boundaries and tabulated layer gradients.
• Thermodynamic variables: equations and tables for pressure, density, specific weight and pressure scale height based on the ideal gas law and hydrostatic equilibrium.
• Transport & kinetic properties: speed of sound, dynamic and kinematic viscosity (Sutherland formula), thermal conductivity, mean free path, air‑particle collision frequency and number density.
• Atmospheric composition: dry clean air composition near sea level and resulting molar mass used for calculations.
• Tabulated data: comprehensive SI‑unit tables of atmospheric properties across altitude ranges (note: one table uses Celsius/mbar/mmHg units).

Applications

• Aerodynamics and aerospace design - performance calculations, flight‑vehicle design and simulation using a common environmental baseline.
• Test reporting and instrument calibration - unifying test conditions so experimental results and calibrations are comparable.
• Meteorology and geophysics - recommended for processing observational data and converting between measured quantities and standard reference values.
• Sensor and avionics development - environmental inputs for sensors, altimeters, and air data systems.

Who should use it

• Aerospace and mechanical engineers, aerodynamicists and flight test teams
• Calibration laboratories and instrument manufacturers
• Meteorologists, atmospheric scientists and geophysicists
• Standards professionals and data analysts needing a reproducible atmospheric reference

Related standards

• ICAO Standard Atmosphere (identical in −2 km to 32 km range)
• WMO Standard Atmosphere (identical in −2 km to 32 km)
• ISO/TC 20 (Technical Committee responsible for aircraft and space vehicle standards)

ISO 2533 remains a practical, widely referenced atmospheric model for engineering calculations, testing and the consistent processing of atmospheric and geophysical observations.