chapter 9- tides

Question 1

diurnal tide

Answer 1

Tide with one high water and one low water each tidal day.

Question 2

semidiurnal tide

Answer 2

Tide with a cyclic high water and low water sequence repeated twice in one day.

Question 3

semidurnal mixed tide

Answer 3

A combines semidiurnal and diurnal tide where the tides reach different heights and lows.

Question 4

tidal datum

Answer 4

The reference level from which ocean depths and and tide heights are measured: the zero tide level

Question 5

minus tide

Answer 5

Low tide level below the tidal datum

Question 6

flood tide

Answer 6

rising tide

Question 7

ebb tide

Answer 7

Falling or dropping tide

Question 8

slack water

Answer 8

The period when tide current slow and reverse from ebb tide to flood tide or flood tide to ebb tide

Question 9

centrifugal force

Answer 9

Outward directed force moving along a curved path: interior force. Without inertia, the moon and sun would crash into eachother.

Question 10

centripetal force

Answer 10

Inward directed gravitational force necessary to keep an object moving in a curved path. Holds earth in orbit.

Question 11

tidal day

Answer 11

24 hours and 50 minutes. The additional 50 minutes is the time it takes to the Earth to turn 12 degrees to bring the starting point on earth back under the moon.

Question 12

spring tide

Answer 12

Result from the alignment of earth, sun and moon during the full moon and new moon

Question 13

neap tide

Answer 13

Results from the moon and earth at a right angle to the sun

Question 14

elliptical orbit

Answer 14

During northern hemisphere winter, sun plays a greater role as tide producer because Earth is closer to the sun

Question 15

free wave

Answer 15

Wave that continues to move at its own natural speed after its generation by a force

Question 16

forced wave

Answer 16

Wave generated by a continuously acting force and caused to move at a speed faster than it freely travels

Question 17

progressive tide

Answer 17

Tide wave moving across the sea surface like a shallow water wave

Question 18

rotary standing tide

Answer 18

Tide resulting from a standing wave moving around the central node of a basin

Question 19

Amphidromic point

Answer 19

Central point (or node) of a rotary tide

Question 20

tidal bore

Answer 20

High tide crest that advances rapidly up an estuary or river as a breaking wave. It produces an abrupt change in water levels.

Question 21

tidal orgins

Answer 21

Due to gravitational attraction between large water bodies & the sun & moon combined with the motions of the Earth & moon.