tuba
tub
Cumulonimbus tuba
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Description
The name "tuba" (Latin: trumpet, tube) refers to a cone- or funnel-shaped cloud formation that extends downward from the base of a cloud. Tuba is a supplementary cloud feature that occurs primarily beneath cumulonimbus, and occasionally beneath cumulus congestus. It is the visible manifestation of a rotating air vortex and represents the precursor or visible form of funnel clouds, waterspouts, and tornadoes. If the vortex reaches the ground or water surface, it is referred to as a tornado or waterspout, respectively.
Identification Features
- Cone-, funnel-, or tube-shaped structure hanging from the cloud base
- Pendant from the base of a cumulonimbus or large cumulus cloud
- Often rotating, sometimes with a visible spinning motion
- Does not always reach the ground (otherwise classified as a tornado or waterspout)
- Typically grey to dark grey in colour
- Occurs in association with severe thunderstorms and supercells
- Can be short-lived and change shape rapidly
Related genera
tuba is not a distinct cloud type, but a supplementary feature that is given in addition to the genus name. It can occur with the following genera: Cu, Cb.
Meteorological Significance
Tuba is a clear warning sign of extreme weather. It indicates strong vertical wind shear and rotation in the atmosphere, which can lead to tornadoes or waterspouts. The appearance of a tuba should be taken as a signal for severe thunderstorms, heavy storm gusts, intense rainfall, and potentially large hail. This phenomenon demands the utmost vigilance and should be classified as an immediate weather hazard. In the United States, it is frequently associated with supercell thunderstorms in Tornado Alley.
Facts
- WMO-Code
- tub
- Height layer
- Vertical clouds
- Typical height
- 0.6 - 1.5 km
- Genus
- CUMULONIMBUS