In a METAR, what does "VV" stand for?

In a METAR, "VV" stands for Vertical Visibility. This designation is used to indicate the vertical visibility into obscuring phenomena, such as fog or heavy rain, when the surface visibility is significantly reduced. It is particularly useful in conditions where horizontal visibility is difficult to measure due to obstructions.

Understanding vertical visibility is crucial for pilots and dispatchers because it provides essential information on how high one can see vertically within the obscuration, which can affect flight operations, particularly during takeoff and landing phases. It helps inform crew decision-making around navigation and safety protocols when flying through areas of low visibility.

For clarity, the other options do not align with standard meteorological terminology used in METAR reports. There is no established terminology for "Visibility Variable," "Vertical Velocity," or "Vapor Visibility" in the context of METARs, making "Vertical Visibility" the clear and correct choice.