Which statement is true about clouds and cloud layers?

The statement regarding cloud layers accurately reflects how ceilings are defined in meteorology. The ceiling is determined by the height of the lowest layer of clouds that is reported as broken or overcast, which is crucial for aviation and weather reporting. A broken cloud layer consists of cloud coverage between 5/8 and 7/8 of the sky, while an overcast layer is completely covered. Knowing the ceiling is essential for pilots and meteorologists since it affects visibility and weather conditions.

The other statements do not align with meteorological principles. For instance, cumulonimbus clouds are typically associated with thunderstorms and severe weather rather than clear conditions. Altocumulus standing lenticular clouds often signal mountain wave activity and may indicate turbulent weather rather than calm. Lastly, cloud layers do indeed affect visibility, particularly if they are low-lying or thick, which can obscure sightlines for both ground-based and airborne observers.