Circulation of flow about a horizontal or nearly horizontal axis that is usually associated with flow over the lee side of a barrier, such as a mountain range. The rotation may extend to the ground, c
ause hazards to aircraft, and carry large amounts of dust aloft.
A turbulent, altocumulus-type cloud formation found in the lee of some large mountain barriers, particularly in the Sierra Nevada near Bishop, California. (Sometimes called roll cloud.) The air in the
cloud rotates around an axis parallel to the range. The term was first applied to clouds of this type in Europe, especially in the Riesengebirge and on Crossfell. Rotor clouds are often associated with lee wave (lenticular) clouds that may be present above.
Any piece, body, or area of ice that is in the process of melting or disintegrating. It is characterized by honeycomb structure, weak bonding between crystals, or the presence of meltwater or seawater
between grains. Rotten ice may appear transparent (and thus dark) when saturated with seawater and so may be easily confused with newly forming black ice.