What identifies the vertical visibility in column 10 for total obscuration?

Vertical visibility in the context of total obscuration refers to the maximum altitude that can be viewed vertically in conditions where visibility is restricted. When reporting this, "VV" stands for "Vertical Visibility." This designation is used to indicate the vertical range of visibility in obscured conditions, such as when fog, smoke, or other phenomena prevent clear sight.

In situations of total obscuration, the vertical visibility is often determined by observing how far one can see upwards through the obscuring medium. The use of "VV" provides a standardized way of reporting this information, which is crucial for pilots and air traffic control personnel when assessing conditions for flight safety.

The other terms listed do not fit this specific designation for vertical visibility. Therefore, "VV" is the recognized and correct term used in aviation weather reporting to indicate vertical visibility when total obscuration is present. Understanding these terms is essential for effective communication of weather conditions in aviation contexts.