Instrument Refresher Course (IRC) Practice Test 2026 - Free IRC Practice Questions and Study Guide

The statement that clouds are always present to indicate mountain wave activity is incorrect; thus, the true answer is that this statement is false. While clouds can often be a visual indicator of mountain wave activity, they do not have to be present for such phenomena to occur. Mountain waves are generated by the flow of air over obstacles, such as mountains, and can manifest even in clear air conditions. When stable air flows over mountain ranges, it can create oscillations that may not produce clouds but still result in turbulence. Therefore, mountain wave activity can exist without the visual cue of clouds, making the assertion incorrect. Understanding this distinction is crucial for pilots and meteorologists when assessing potential turbulence areas, particularly in mountainous regions.