What conditions lead to the reporting of vertical visibility?

Vertical visibility is reported in situations where the atmosphere is obscured, particularly due to phenomena such as fog, heavy precipitation, or other factors that prevent clear visibility in the vertical direction. This reporting is crucial for pilots and aviation operations as it provides an understanding of the degree of visibility available for takeoff and landing, especially in conditions that restrict upward visibility.

When these obscuring conditions occur, vertical visibility can be used as a measurement to assess how far one can see upward from a certain point, thus providing critical information when the sky's visibility is compromised. This leads to enhanced safety in flight operations during poor weather conditions. In cases where the lowest ceiling is low, vertical visibility gives a clear indicator of whether it is safe to conduct operations.