tides and currents Flashcards
the rise and fall of water
tide
the periodic horizontal movement of the water
tidal current / tidal stream
the periodic motion of the waters of the sea due to differences in the attractive forces of various celestial bodies
tidal phenomenon
the maximum height reached by tide
high tide / high water
the minimum level to which the tide falls
low tide / low water
the period at HW or LW during which there is no sensible change of level of tide
stand
the difference in height between consecutive high and low waters
range
vertical distance from the chart sounding datum to the water surface at any stage of the tide
height of tide
the vertical distance from the chart sounding datum to a high water datum
rise of tide
there are two high and two low waters each tidal day with relatively small inequality in the high and low water heights
semidiurnal tide
tides on the atlantic coast of the US
semidiurnal tide
only a single high and single low water occur each tidal day
diurnal tide
tides on the gulf of mexico (N. shore), java sea, gulf of tonkin
diurnal tide
characterized by a large inequality in the high water heights, low water heights or in both
mixed tide
tides on the pacific coast of the US
mixed tide
tides with higher high and lower low
spring tides
occur at time of new and full moon (sun and moon are in conjunction and at opposition with the earth
spring tides
tides with lower high and higher low
neap tides
occur at times of first and third quarters (sun and moon are in quadrature with the earth
neap tides
high and low waters occur at about the same time each day due to the effect of the sun.
ex. areas of S. pacific and indonesia
solar tide
at such places there is often a slight fall or rise in the middle of the high and low water period
the practical effect is to create a longer period of stand at high or low tide
double low water (as at hoek van holland) and double high water (as at southampton, england)
occurs when the moon is at the point in its orbit nearest the earth. the lunar semidiurnal range is increased
perigean tide
occurs when the moon is farthest from the earth. the semidiurnal range is decreased
apogean tide
occurs when the moon is at its maximum semi-monthly declination N or S
diurnal effect is at a maximum
tropic tide
occurs when the moon crosses the equator
diurnal effect is minimum
equatorial tide
