Vertical Visibility - the distance that an observer can see vertically into a surface-based obscuring phenomenon, such as fog, rain, or snow ...
VERTICAL VISIBILITY The distance an observer can see vertically into an undefined ceiling, or the height corresponding to the top of a ceiling light projector beam, ...
vertical visibility—The distance one can see upward into a surface based obscuration; or the maximum height from which a pilot in flight can recognize the ground through a surface based obscuration.
If the sky is totally obscured, then it is the height of the vertical visibility. See measured ceiling and variable ceiling.
The balloon can also be used to measure the vertical visibility into a layer of fog or blowing snow. In this case the balloon will begin to fade as soon as it is released, so the vertical visibility is when the balloon disappears.
It always includes the cloud height or vertical visibility, sky cover, visibility, obstructions to vision, certain atmospheric phenomena, and wind speed and direction that prevail at the time of the observation.
Any atmospheric phenomenon, except clouds, that restricts vertical visibility (e.g., dust, rain, snow, etc.).
Obscuring Phenomena
Any atmospheric phenomenon, except clouds, that restricts vertical visibility (e.g., dust, rain, snow, etc.).
Ceilometer A device used to evaluate the height of clouds or the vertical visibility into a surface-based obscuration.
Forecast sky cover (height and amount of cloud bases), cloud tops, visibility (including vertical visibility), weather, and obstructions to vision are described for a corridor 25 miles either side of the route.
CEILING The lowest cloud layer that is reported as broken or overcast. If the sky is totally obscured, then it is the height of the vertical visibility. Related terms: measured ceiling and variable ceiling ...
 See also: Visibility, Cloud, Water, Weather, Temperature
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