What is the standard lapse rate value used in calculating mean sea level pressure?

What is the standard lapse rate value used in calculating mean sea level pressure?

• A. 1.98°C/1000'
• B. 2.00°C/1000'
• C. 1.50°C/1000'
• D. 2.50°C/1000'

Answer: (A)

Temperature decreases with height at a defined rate in the standard atmosphere, and that lapse rate is used in the hypsometric equation to relate pressure differences to height when estimating mean sea level pressure. The precise value defined for aviation and meteorology is 1.98°C per 1000 feet, meaning air cools by about 1.98°C for every 1000 feet you gain in altitude. This exact figure is used because it matches the International Standard Atmosphere; using a rounded figure like 2.00°C/1000' is close but slightly less accurate for calculations. The other options do not match the standard gradient and would introduce small errors in MSL pressure computations.

Temperature decreases with height at a defined rate in the standard atmosphere, and that lapse rate is used in the hypsometric equation to relate pressure differences to height when estimating mean sea level pressure. The precise value defined for aviation and meteorology is 1.98°C per 1000 feet, meaning air cools by about 1.98°C for every 1000 feet you gain in altitude. This exact figure is used because it matches the International Standard Atmosphere; using a rounded figure like 2.00°C/1000' is close but slightly less accurate for calculations. The other options do not match the standard gradient and would introduce small errors in MSL pressure computations.