Grunt Productions 2000 Ocean Waves Ocean Waves Capillary Capillary Gravity Gravity Wind Wind generated generated Tides Tides Tsunamis Tsunamis Seiches Seiches
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Grunt Productions 2000
Ocean WavesOcean Waves
CapillaryCapillary
GravityGravityWind Wind
generatedgenerated
TidesTides
TsunamisTsunamisSeichesSeiches
Grunt Productions 2000
Tides
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New Moon
Full Moon
First Quarter
Third Quarter
Lunar Phases
Grunt Productions 2000 http://www.oceanservice.noaa.gov/education/kits/tides/media/supp_tide06a.html
Moon’s faster orbits about the Earth, compared to Earth’s orbit about the Sun, means that “Spring” and “Neap” tides aredefined by theLunar orbit.
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New Moon
Full Moon
Spring Tides occur when the lunar and solar gravitational pulls add up
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First Quarter
Third Quarter
Neap Tides occur when lunar and solar gravitational pulls are mutually perpendicular
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Tides can beTides can be
SPRING and NEAP, SPRING and NEAP, depending on the relative depending on the relative positions of Sun and Moonpositions of Sun and Moon
DIURNAL, SEMIDIURNAL or DIURNAL, SEMIDIURNAL or MIXED, depending on their MIXED, depending on their daily cyclesdaily cycles
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Wave interference can be Wave interference can be constructive or destructiveconstructive or destructive
Grunt Productions 2000 Constructive Constructive interferenceinterference
Constructive Constructive interferenceinterference
Constructive Constructive interferenceinterference
Destructive Destructive interferenceinterference
Destructive Destructive interferenceinterference-1
0
1
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0.5
1
0 90 180 270 360
AABB
CC
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Tides can be
1. Diurnal: or once daily
2. Semidiurnal or twice daily
and
3. Mixed
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Semidiurnal tides are more common than diurnal and mixed tides
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An amphidromic point is a point within a tidal system where the tidal range is almost zero, i.e., there is almost no vertical move-ment. Such points occur because of the coriolis effect and interference within oceanic basins and bays creating a wave pattern which rotates around the amphidromic point. These points are located at Tahiti, off the coast of Newfoundland, near the South Shetlands, midway between Rio de Janeiro and Angola, at three points in the North Sea and at several other locations in the Pacific, Atlantic and Indian oceans. The island of Madagascar is an amphidromic point, as is New Zealand.
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Tsunamis
Grunt Productions 2000
The travel-path of the tsunami of April 1, 1946
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Active ocean-
continent margins
should expect
tsunamis more
frequently than the passive
ones
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The map below shows the position of the leading wave of a tsunami generated by a 1979 earthquake offshore Colombia, South America*. These contours are for the tsunami arrival times in hours.
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Consider an earthquake with its epicenter at Honolulu, Hawaii. The corresponding tsunami travel times (in hours) from Hawaii are given in this map of the Pacific Ocean.
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No matter where an earthquake
occurs in the Pacific, Hawaii is barely 15 hours
away, at the most!
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The Dec 2004 Asian Tsunami: The Dec 2004 Indian Ocean tsunami was
produced by perhaps the strongest earthquake of the past 100 years. It occurred in the Java trench,
off Bandar Aceh in north-western Sumatra. This animation was produced by the
National Oceanic and Atmospheric Administration
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