Oceanography -- Chapter 11

Front 1

mixed tide

Back 1

A complex tidal cycle, usually with two high tides and two low tides of unequal height per day.

Front 2

tidal tatum

Back 2

The reference level (0.0) from which tidal height is measured.

Front 3

tsunami

Back 3

Long-wavelength shallow-water wave caused by rapid displacement of water. See also seismic sea wave.

Front 4

seiche

Back 4

Pendulum-like rocking of water in an enclosed area; a form of standing wave that can be caused by meteorological or seismic forces, or that may result from normal resonance excited by tides.

Front 5

high tide

Back 5

The high water position corresponding to a tidal crest.

Front 6

storm surge

Back 6

An unusual rise in sea level as a result of the low atmospheric pressure and strong winds associated with a tropical cyclone. Onrushing seawater precedes landfall of the tropical cyclone and causes most of the damage to life and property.

Front 7

dynamic theory of tides

Back 7

Model of tides that takes into account the effects of finite ocean depth, basin resonance, and the interference of continents on tide waves.

Front 8

tidal current

Back 8

Mass flow of water induced by the raising or lowering of sea level owing to passage of tidal crests or troughs. See also ebb current; flood current.

Front 9

low tide

Back 9

The low water position corresponding to a tidal trough.

Front 10

seismic sea wave

Back 10

Tsunami caused by displacement of the Earth along a fault. (Earthquakes and seismic sea waves are caused by the same phenomenon.)

Front 11

tide

Back 11

Periodic short-term change in the height of the ocean surface at a particular place, generated by long-wavelength progressive waves that are caused by the interaction of gravitational force and inertia. Movement of Earth beneath tide crests results in the rhythmic rising and falling of sea level.

Front 12

tidal bore

Back 12

A high, often breaking wave generated by a tide crest that advances rapidly up an estuary or river.

Front 13

equilibrium theory of tides

Back 13

Idealized model of tides that considers Earth to be covered by an ocean of great and uniform depth capable of instantaneous response to the gravitational and inertial forces of the sun and moon.

Front 14

neap tide

Back 14

The time of smallest variation between high and low tides occurring when Earth, moon, and sun align at right angles. Neap tides alternate with spring tides, occurring at two-week intervals.

Front 15

flood current

Back 15

Water rushing into an enclosed harbor or bay because of the rise in sea level as a tide crest approaches.

Front 16

mean sea level

Back 16

The height of the ocean surface averaged over a few years time.

Front 17

slack water

Back 17

A time of no tide-induced currents that occurs when the current changes direction.

Front 18

diurnal tide

Back 18

A tidal cycle of one high tide and one low tide per day

Front 19

solar tide

Back 19

Tide caused by the gravitational and inertial interaction of the sun and Earth.

Front 20

tidal range

Back 20

The difference in height between consecutive high and low tides.

Front 21

spring tide

Back 21

The time of greatest variation between high and low tides occurring when Earth, moon, and sun form a straight line. Spring tides alternate with neap tides throughout the year, occurring at two-week intervals.

Front 22

standing wave

Back 22

A wave in which water oscillates without causing progressive wave forward movement. There is no net transmission of energy in a standing wave.

Front 23

tidal wave

Back 23

The crest of the wave causing tides. Another name for a tidal bore. (Not a tsunami or seismic sea wave.)

Front 24

ebb current

Back 24

Water rushing out of an enclosed harbor or bay because of the fall in sea level as a tide trough approaches.

Front 25

meteorological tide

Back 25

A tide influenced by the weather. Arrival of a storm surge will alter the estimate of a tide's height or arrival time; as will a strong, steady onshore or offshore wind.

Front 26

lunar tide

Back 26

Tide caused by gravitational and inertial interaction of moon and Earth.

Front 27

node

Back 27

The line or point of no wave action in a standing pattern. See also amphidromic point.

Front 28

semidiurnal tide

Back 28

A tidal cycle of two high tides and two low tides each lunar day, with the high tides of nearly equal height.