When the contraction BKN is present in an observation, how many eighths of the sky is covered?

The contraction BKN stands for "Broken" when describing cloud cover in aviation weather reports. When BKN is used in an observation, it indicates that between 5/8 and 7/8 of the sky is covered by clouds. This terminology is part of a standardized way to report cloud coverage, which divides the sky into eighths.

Thus, since BKN refers specifically to this level of coverage in the range of 5 through 7 eighths, it clearly supports the choice given. Understanding these terms is crucial for interpreting weather reports accurately, especially for flight operations where cloud cover can significantly impact safety and navigation.