Seiche
A seiche (pronounced SAYSH) or an underwater wave is an underwater, irregular fluctuation or rhythmic rocking of the water level of a lake, first noted in Lake Geneva, Switzerland. Observers on the surface may not know a seiche is happening.Seiches are common between warm and cold-water layers, notably in Loch Ness, Scotland, and some evidence cited for the Loch Ness monster and the Lake Champlain monster (see also Lake monster and Sea monster) may trace to seiches.
Small rhythmic seiches are almost always present on larger lakes, and the frequency of the oscillation is determined by the size of the body, its depth and contours, and the water temperature. On the North American Great Lakes seiche is often called slosh. It is always present but is usually unnoticeable except during periods of unusual calm.
Major seiches often occur during earthquakes and may be caused by wind or underwater landslides. Lake Erie, because of its shallowness and elongation can occasionally have wind caused extreme seiches of up to 15 feet (5 meters) between the ends. The first appearance is similar to a storm surge like those caused by hurricanes along ocean coasts, but the seiche effect can cause oscillation back and forth across the lake for some time. Hurricane Hazel piled up water along the northwestern Lake Ontario shoreline near Toronto, causing extensive flooding, and established a seiche that subsequently caused flooding along the south shore.
Seiche is also a French term for a type of cuttlefish.
General:
External links and references
On aquatic monsters:
The French term: