Science / Weather / Wall Cloud: An abrupt lowering of a cloud from its parent cloud base, a cumulonimbus or supercell, with no visible precipitation underneath. Forming in the area of a thunderstorm updraft, or inflow area, it exhibits rapid upward movement and cyclonic rotation. It often develops before strong or violent tornadoes.
Wall Verb Synonyms: screen, partition, divider, enclosure, separator, bulkhead, barrier, obstruction, obstacle, impediment, block, fence
Science / Weather / Rotor Cloud: An altocumulus cloud formation that can be found in the lee of a mountain or similar barrier. The air rotates around a horizontal axis, creating turbulence. Altocumulus lenticularis is an example. MORE
Science / Weather / Roll Cloud: A relatively rare, low-level, horizontal, tube-shaped cloud. Although they are associated with a thunderstorm, they are completely detached from the base of the cumulonimbus cloud. MORE