waterspouts. Unlike the related phenomenon associated with severe thunderstorms, cold-air funnels are generally associated with partly cloudy skies in the wake of cold fronts, especially associated with certain low pressure systems, or in association with atmospheric boundaries such as lake and sea breezes or outflow boundaries. The larger scale weather conditions are characterized by particularly cold air aloft over relatively warmer low level air, leading to high lapse rates, and often by high environmental vorticity yet relatively meager vertical wind shear. The funnels develop where atmospheric instability and moisture are sufficient to support towering cumulus clouds but typically limited to no or to little precipitation. Cold-air funnels, although weak, may persist for several minutes, and areas of intermittently forming funnel clouds may occur for tens of minutes. Multiple such areas of activity may form within the same region during afternoon heating. Cold-air funnels appears to be a diurnal phenomenon, weakening and eventually dissipating with loss of solar heating. When precipitation does develop, the associated downdraft tends to cause rapid demise of the cold-air funnels. The mixing of cooler air in the lower troposphere with air flowing in a different direction in the middle troposphere causes the rotation on a horizontal axis, which, when deflected and tightened vertically by convective updrafts, forms a vertical rotation that can cause condensation to form a funnel cloud. Cold-air funnel clouds are a common sight along the Pacific Coast of the United States, particularly in the spring or fall. On July 29, 2013, a cold-core funnel cloud touched down as an EF0 tornado in Ottawa, Ontario, Canada, causing extensive damage in the form of downed trees on a golf course. No advance weather watches or warnings were issued by Environment Canada, and the tornado was spawned from one of the few non-severe storm clouds moving through the area. Other funnel clouds Other funnel clouds include shear or "high based" funnels, which are ephemeral, small, and weak funnels associated with small cumulus clouds, often even those rooted aloft above the boundary or surface layer, and in "fair weather" conditions. Small funnel clouds, such as some occurring within vicinity of mountains, occur by unknown processes. Shear funnels might also occur with weak transient circulations at the cloud base of thunderstorms. Mesoanticyclones, which accompany mesocyclones, often exhibit these funnel clouds. Brief funnels also are observed with some rear flank downdrafts (RFDs) (within inflow or outflow areas, and especially