Barometric pressure at standard conditions is measured as which of the following?

Barometric pressure at standard conditions is measured as which of the following?

• A. 30.00 inches of mercury or 15.0 PSI
• B. 29.92 inches of mercury or 14.7 PSI
• C. 28.50 inches of mercury or 13.5 PSI
• D. 31.00 inches of mercury or 16.0 PSI

Answer: (B)

Standard barometric pressure at sea level is defined as one atmosphere, which equals 29.92 inches of mercury. In pounds per square inch, that same pressure is about 14.7 psi. This set value—29.92 inHg and 14.7 psi—is the reference used in aviation and meteorology for calibrating instruments and describing altitude in relation to the standard atmosphere. The other options are simply not the defined standard: they are close or farther off from 29.92 inHg, which is why they aren’t the correct standard values.

Standard barometric pressure at sea level is defined as one atmosphere, which equals 29.92 inches of mercury. In pounds per square inch, that same pressure is about 14.7 psi. This set value—29.92 inHg and 14.7 psi—is the reference used in aviation and meteorology for calibrating instruments and describing altitude in relation to the standard atmosphere. The other options are simply not the defined standard: they are close or farther off from 29.92 inHg, which is why they aren’t the correct standard values.