EM 1110-2-1100 (Change 1)
31 Jul 03
TROCHOIDAL WAVE
A theoretical, progressive oscillatory wave first proposed by Gerstner in 1802 to describe the surface profile and
particle orbits of finite amplitude, nonsinusoidal waves. The wave form is that of a prolate cycloid or trochoid, and the fluid
particle motion is rotational as opposed to the usual irrotational particle motion for waves generated by normal forces.
Compare IRROTATIONAL WAVE
TROPICAL CYCLONE
See HURRICANE
TROPICAL STORM
A tropical cyclone with maximum winds less than 34 m/sec (75 mile per hour). Compare with HURRICANE or
TYPHOON (winds greater than 34 m/sec).
TROUGH
A long and broad submarine DEPRESSION with gently sloping sides.
TROUGH OF WAVE
The lowest part of a waveform between successive crests. Also, that part of a wave below still-water level.
TSUNAMI
A long-period water wave caused by an underwater disturbance such as a volcanic eruption or earthquake. Also
SEISMIC SEA WAVE. Commonly miscalled "tidal wave."
TURBIDITY
(1) A condition of a liquid due to fine visible material in suspension, which may not be of sufficient size to be seen
as individual particles by the naked eye but which prevents the passage of light through the liquid. (2) A measure of fine
suspended matter in liquids.
TURBIDITY CURRENT
A flowing mass of sediment-laden water that is heavier than clear water and therefore flows downslope along the
bottom of the sea or a lake.
TURBULENT FLOW
Any flow which is not LAMINAR, i.e., the stream lines of the fluid, instead of remaining parallel, become confused
and intermingled.
TYPHOON
See HURRICANE. The term typhoon is applied to tropical cyclones in the western Pacific Ocean.
A-84
Appendix A Glossary of Coastal Terminology
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