Wall cloud
| Wall cloud (Murus) | |
|---|---|
A rain-free base with a wall cloud lowering in the foreground and precipitation in the background. Taken in Needmore, Texas. | |
| Abbreviation | Cb mur. |
| Symbol | |
| Genus | Cumulonimbus (heap, rain) |
| Species |
|
| Variety | None |
| Altitude | 500-16,000 m (2,000-52,000 ft) |
| Classification | Family C (Low-level) |
| Appearance | A dark cloud feature that protrudes from the base of a cumulonimbus more popularly known as a wall cloud. |
| Precipitation | Very common nearby, but not under : Rain, Snow, Snow pellets or Hail, heavy at times |
A wall cloud (murus or pedestal cloud) is a large, localized, persistent, and often abrupt lowering of cloud that develops beneath the surrounding base of a cumulonimbus cloud and from which tornadoes sometimes form. It is typically beneath the rain-free base (RFB) portion of a thunderstorm, and indicates the area of the strongest updraft within a storm. Rotating wall clouds are an indication of a mesocyclone in a thunderstorm; most strong tornadoes form from these. Many wall clouds do rotate; however, some do not.