Which type of turbulence is caused by obstructions such as buildings or mountains?

The correct answer is mechanical turbulence, which occurs when airflow is disrupted by physical obstructions such as buildings, hills, or mountains. As wind flows over and around these structures, it creates turbulence in the surrounding air. This disruption can lead to varying wind speeds and directions, generating turbulence that can affect aircraft operating nearby.

Understanding mechanical turbulence is essential for pilots because it can impact flight stability, control, and safety, particularly during takeoff and landing phases when aircraft are flying at lower altitudes and speeds. Recognizing areas that may be prone to mechanical turbulence allows pilots to adjust their approach or flight path to mitigate its effects.

In contrast, clear air turbulence typically occurs at higher altitudes in clear air, far from any significant weather systems or obstructions. Wake turbulence is caused by an aircraft's passage through the air and is specifically related to the vortices left behind by its wings. Thermal turbulence results from uneven heating of the Earth's surface, which leads to rising and descending air currents, commonly found under towering cumulus clouds. Understanding these distinctions helps pilots anticipate and respond appropriately to various turbulence types encountered in flight.