Which pressure corresponds to an altitude of approximately 30,000 ft?

• A. 500 mb
• B. 300 mb
• C. 700 mb
• D. 850 mb

Answer: (B)

At an altitude of approximately 30,000 feet, the standard atmospheric pressure is typically around 300 millibars (mb). This relationship between altitude and pressure is based on the standard atmosphere model, which shows how pressure decreases with an increase in height. Generally, at sea level, the average pressure is about 1013.25 mb, and as altitude increases, the pressure decreases due to the thinning of the air.

At 30,000 feet, the atmosphere has lost a significant amount of its weight above, resulting in much lower pressure, which is consistent with the reduction down to about 300 mb. This pressure level is commonly observed at that altitude in standard atmospheric conditions. Understanding these pressure readings is integral for pilots and meteorologists as they help in flight planning and turbulence expectations.