What does an obscuration represent in terms of sky visibility?

An obscuration in weather terminology refers to conditions where visibility is significantly impaired, often due to phenomena like fog, smoke, rain, or snow. When an obscuration is present, it usually means that the view of the sky (and thus conditions for flight, observation, etc.) is severely impacted.

The correct choice indicates that when visibility is described as being obscured, it is completely hidden from view. This means that pilots or observers cannot see the sky at all, which can have serious implications for flying, as it affects the ability to navigate using visual references.

Other options describe varying degrees of visibility, such as being visible or partially hidden, which do not accurately capture the essence of an obscuration. Obscurations imply a total blockage of sight, making the correct interpretation crucial for safety and operational awareness in aviation.