FAA Aircraft Dispatcher Practice Exam

Which of these factors contributes to the formation of a squall line?

1. A line of static pressure

2. Meeting of warm and cold air masses

3. High humidity levels

4. Steady winds from one direction

The correct answer is: Meeting of warm and cold air masses

The correct answer highlights the significance of the interaction between warm and cold air masses in the formation of a squall line. A squall line is a specific type of convective weather pattern that occurs when a line of thunderstorms develops, typically ahead of a cold front. When warm, moist air rises and encounters a mass of cooler, denser air, it leads to instability in the atmosphere, which is a crucial element for thunderstorm development. The lifting of the warm air results in cloud formation and can produce severe weather conditions such as heavy rain and strong winds characteristic of squall lines. The other factors mentioned do not directly contribute to the formation of a squall line in the same dynamic way. A line of static pressure does not foster the necessary uplift mechanisms; high humidity levels alone, while they do support cloud development, do not cause the essential lifting necessary for squall line formation; and steady winds from one direction may not help in creating the required airflow patterns that facilitate the convergence of different air masses needed for a squall line to emerge. Thus, the interaction of warm and cold air masses stands out as the primary driver for the formation of these weather phenomena.