PPL Aeronautical Knowledge 4

Question 1

What is the standard atmospheric pressure at sea level?

Accepted Answer

1013.2 hPa / 29.92 inHg

Answer

Standard sea-level pressure is 29.92 inHg or 1013.2 hPa.

Question 2

The standard temperature lapse rate in the troposphere is approximately:

Accepted Answer

2°C per 1,000 feet

Answer

Temperature decreases about 2°C per 1,000 feet in the standard atmosphere.

Question 3

A temperature/dew point spread that is small and decreasing indicates:

Accepted Answer

Increasing likelihood of fog or clouds

Answer

A narrowing temperature-dew point spread signals rising humidity and possible fog or low clouds.

Question 4

Which type of fog forms on clear nights with light winds due to terrestrial cooling?

Accepted Answer

Radiation fog

Answer

Radiation fog forms overnight when the ground cools the air to its dew point.

Question 5

The presence of towering cumulus clouds is a sign of:

Accepted Answer

Unstable air with possible turbulence

Answer

Towering cumulus indicate unstable air and the potential for turbulence and thunderstorms.

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