At manual reporting stations, the contraction for clear skies is:

The contraction for clear skies at manual reporting stations is "SKC." This abbreviation stands for "sky clear" and is used in meteorological reports to indicate that there are no significant cloud cover or obstructions in the sky. It is a standardized term widely recognized in weather observations, making it essential for accurate communication among meteorologists and pilots.

Having "SKC" instead of writing out "sky clear" contributes to the efficiency and brevity of weather reports, which is crucial in aviation for quick and clear understanding of weather conditions. Using clear abbreviations helps pilots in planning their flights, especially in terms of visibility and weather forecasting.

Understanding the meanings of these abbreviations is important for anyone involved in aviation and meteorology, as they are foundational to interpreting weather data effectively. Other options do not represent the standard contraction for clear skies, which is why they are not correct choices.