tide
the periodic rise and fall of the surface of the ocean and connected bodies of water resulting from the gravitational attraction of the moon and sun acting unequally on different parts of Earth
barycenter
the center of mass of a system
gravitational force
the force of attraction that exists between any two bodies in the universe that is proportional to the product of their masses and inversely proportional to the square of the distance between the centers of their masses
Newton's law of universal gravitation
an equation that quantifies gravitational force between two bodies
zenith
the point on the celestial sphere directly over the observer
nadir
the point on the celestial sphere directly opposite the zenith and directly beneath the observer
centripetal force
a center-seeking force that tends to make rotating bodies move toward the center of rotation
resultant force
the difference between the provided gravitational force of various bodies and the required centripetal force
tide-generating forces
the magnitude of the centripetal force required to keep all particles of Earth having identical mass moving in identical circular paths required by the movements of the earth-Moon system is identical
lunar bulges
a tidal bulge that goes away and towards the moon
tidal period
the time that elapses between successive high tides
lunar day
the time interval between two successive transits of the Moon over the meridian
solar day
the 24-hour period during which Earth completes one rotation on its axis
solar bulges
tidal bulges oriented toward the Sun and away from the Sun
flod tide
a rising tide
ebb tide
a tide moving away from the shore
new moon
the phase of the Moon that occurs when the Sun and the Moon are in conjuncction; that is, the are both on the same side of Earth
full moon
the phase of the Moon that occurs when the Sun and Moon are in opoposition; that is, they are on opposite sides of Earth
quarter moon
first- and third- quarter moon phases which occur when the Moon is in quadrature about one week after the new mon and full moon phases
tidal range
the difference between high and low tide water levels over any designated time interval
spring tide
a tide of maximum range occuring about every two weeks when the Moon is either new or full moon phase
syzygy
either of the two points in the orbit of the Moon when the Moon lies in a straight line with the Sun and Earth
neap tide
tides of minimal range occurring about every two weeks when the Moon is in either first- or third-quarter moon phase
quadrature
the state of the Moon during the first- and third-quarter moon phases when the Sun and the Moon are at right angles relative to the Earth
waxing crescent
the Moon when it is between new moon and first-quarter phases
waxing gibbous
the Moon when it is between first-quarter and full moon phases
waning crescent
the Moon when it is between third-quarter and new moon phases
waning gibbous
the Moon when it is between full moon and third-quarter phases
declination
the angular distance of the Sun or Moon above or below the plane of Earth's equator
ecliptic
the plane of the center of the Earth-Moon system as it orbits around the Sun
perihelion
that point on the orbit of a planet or comet around the Sun that is closest to the Sun
aphelion
the point in the orbit of a planet or comet where it is farthest from the Sun
perigee
the point on the orbit of an Earth satellite that is nearest Earth
apogee
the point in the orbit of the Moon or an artificial satellite that is farthest from Earth
proxigean
a tidal condition of extremely large tidal range that occurs when spring tides coincide with the perigee
amphidromic point
a nodal point in the oean or sea around which the crest of the tide waves rotates during one tidal period
cotidal lines
a line connecting points where high tide occurs simultaneously
diurnal tide pattern
a tidal pattern exhibiting one high tide and one low tide during a tidal day
semidiurnal tidal pattern
a tidal pattern exhibiting two high tides and two low tides per tidal day with small inequalities between successive highs and successive lows
mixed tidal pattern
a tidal pattern exhibiting two high tides and two low tides per tidal day with a marked dirurnal inequality
rotary current
a tidal current that is observed in the oen ocean and makes one complete rotaion during a tidal period
reversing current
the tide current as it occurs at the margins of landmasses
flood current
a tidal current associated with increasing height of the tide, generally moving toward the shore
ebb current
the flow of water seaward during a decrease in the height of the tide
high slack water
the period of time associated with the peak of high tide when there is no visible flow of water into or out of bays and rivers
low slack water
the period of time associated with the peak of low tide when there is no visible flow of water into or out of bays and rivers
whirlpool
a rapidly rotating current of water