What type of clouds should pilots be particularly cautious of?

Pilots should be particularly cautious of cumulonimbus clouds because these clouds are associated with severe weather conditions, including thunderstorms, heavy precipitation, turbulence, and even hail. Cumulonimbus clouds can develop rapidly and reach great heights, often resulting in unpredictable and hazardous flying conditions. They can produce updrafts and downdrafts that pose significant risks to aircraft during ascent and descent. Moreover, these clouds can also contain electrical activity, contributing to lightning hazards. Recognizing the potential dangers these clouds present is critical for pilot safety, making them a primary concern in flight operations.