Final answer:
The significance of seeing 'CB' in the sky cover section of a METAR report is that it indicates the presence of hazardous weather conditions associated with cumulonimbus clouds.
Step-by-step explanation:
In a METAR (Aviation Routine Weather Report) sky cover section, the code 'CB' refers to cumulonimbus clouds. Cumulonimbus clouds are large, vertically developed clouds that are associated with heavy rain, thunderstorms, and other severe weather conditions.
The significance of seeing 'CB' in the sky cover section of a METAR report is that it indicates the presence of hazardous weather conditions. Pilots and meteorologists analyze this information to assess the potential for turbulence, lightning, heavy precipitation, and other hazards that can affect aviation operations.
For example, if a METAR report includes 'SKC' (clear sky) in the sky cover section, it means there are no clouds present. However, if it includes 'BKN' (broken clouds) or 'OVC' (overcast clouds), it indicates a different level of cloud coverage. 'CB' specifically alerts pilots and meteorologists to the presence of cumulonimbus clouds, which can pose significant risks to aviation.