Which model of atmosphere uses a sea-level pressure of 29.92 inches of mercury and a lapse rate of about 3.5 °F per 1,000 feet?

• A. Standard Atmosphere
• B. International Standard Atmosphere
• C. Mean Sea Level Atmosphere
• D. Hydrostatic Atmosphere

Answer: (A)

The standard atmosphere is the reference model used in aviation to relate altitude to pressure, temperature, and density. It fixes sea‑level pressure at 29.92 inches of mercury and uses a temperature lapse rate of about 3.5°F per 1,000 feet (roughly 2°C per 1,000 ft). This combination provides a simple, consistent baseline for calculating how the air changes with altitude, which in turn supports density altitude, true airspeed, and performance planning. The International Standard Atmosphere uses essentially the same baseline values, but when the question specifies those exact numbers—29.92 inHg and a lapse rate near 3.5°F/1,000 ft—it points to the Standard Atmosphere. The other terms aren’t the recognized model used for these aviation calculations.