##### Explorations: The Standard Atmosphere

The standard atmosphere is a table of the properties of the atmosphere, including temperature and pressure, at various altitudes from sea level on up. You can think of it as a set of figures for the average pressure, temperature, and air density for various altitudes in the middle latitudes.

Engineering calculations for aircraft design and the performance calculations, such as length of runway needed to take off, are based on the standard atmosphere. The standard atmosphere also shows, in a general way, the pressures and temperatures to be expected at various altitudes.

The standard atmosphere is based on mathematical formulas that reduce temperature and pressure by certain amounts as altitude is gained. The results are close to averages of balloon and airplane measurements in the middle latitudes.

A meteorology text with a standard atmosphere table that includes both international (metric) and U.S. units is C. Donald Ahrens, Meteorology Today: An Introduction to Weather, Climate, and the Environment, Fifth Edition, (St. Paul, MN: West Publishing Company, 1994), 549. Most other texts have altitudes in meters and temperatures in Fahrenheit.

A good, brief history of the standard atmosphere (and explanations of why it was developed and how it is used in aeronautics) is found in John David Anderson, An Introduction to Flight, (New York: McGraw–Hill Professional, 2004), 101–121. This is a basic aerodynamics textbook.

###### Other Sources of Standard Atmosphere Data
• USATODAY.com’s abbreviated tables (in both U.S. and metric units)
• Embry–Riddle Aeronautical University’s Standard Atmosphere Calculator
• The standard atmosphere is also used for an important quantity that pilots use in performance calculations, known as the density altitude. An article in the July 2003 issue of the Aircraft Owners and Pilots Association’s Flight Training Magazine explains what density altitude is and why and how pilots use it.

The AMS Weather Book:The Ultimate Guide to America’s Weather
Jack Williams
With Forewords by Rick Anthes and Stephanie Abrams
©2009, 368 pages, 140 color plates, 70 halftones 8-1/2 x 10-7/8
Cloth \$35.00 ISBN: 9780226898988