Which contraction denotes three-eighths of the sky covered by a surface-based obstruction?

The contraction that denotes three-eighths of the sky covered by a surface-based obstruction is "SCT," which stands for "scattered." In aviation weather reports, "scattered" indicates that there are some clouds or obstructions present in the sky, but they do not significantly block the view. Specifically, "SCT" implies that 3/8 of the sky is obscured, allowing for a majority of the sky to remain visible.

This designation is important for pilots and meteorologists as it helps them assess visual flight rules (VFR) conditions. Understanding the extent of cloud coverage is crucial for navigating and ensuring safe flight operations. Other terms like "OVC" (overcast), "BKN" (broken), and "CLR" (clear) refer to different levels of cloud coverage: "OVC" indicates the sky is completely covered, "BKN" suggests more than half the sky (between 5/8 and 7/8) is obscured, while "CLR" means no significant obstructions are present. Thus, "SCT" is the correct choice for three-eighths coverage.