banner cloud[′ban·ər ‚klau̇d]
A cloud plume often observed to extend downwind from isolated mountain peaks, even on otherwise cloud-free days. Also known as cloud banner.
A cloud plume extending downward from a mountain peak and suggesting a banner. This is, often, prevalent on a cloudless day. The cloud may be formed by reduced atmospheric pressure on the leeward side of the peak or may consist of drifting snow.