1.Gravitational pull of the moon and sun 2.Centripetal force of the rotating Earth Tides are...
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Transcript of 1.Gravitational pull of the moon and sun 2.Centripetal force of the rotating Earth Tides are...
1.Gravitational pull of the moon and sun
2.Centripetal force of the rotating Earth
Tides are generated by:
Tides are generated by:• the gravitational pull of the moon and sun
- moon has 2x greater gravitational pull than the sun - sun is 10 million x more massive than the
moon and is 390 times farther away
Centripetal force
CENTRIPETAL
GRAVITATIONAL FORCE
GRAVITATIONAL & CENTRIPETAL
• Diurnal Tide: 24 hr 50 min cycle
• Semi Diurnal Tide: 12 hr 25 min cycle
• Mixed Tide: 12 hr 25 min cycle
Tidal Cycles
• High water: a water level maximum ("high tide") • Low water: a water level minimum ("low tide") • Tidal range: the difference between high and low
tide• Spring Tide: full moon and new moon (14.77 days)• Neap Tide: 1st quarter and 3rd quarter (14.77 days)
Description of tides
Intertidal zoneHigh tide
Low tide
The monthly tidal cycle(29½ days)
About every 7 days, Earth alternates between:– Spring tide
• Alignment of Earth-Moon-Sun system (syzygy)• Lunar and solar bulges constructively interfere• Large tidal range
– Neap tide• Earth-Moon-Sun system at right angles (quadrature)• Lunar and solar bulges destructively interfere• Small tidal range
Earth-Moon-Sun positions and the monthly tidal cycle
Spring TideHighest high tide and lowest low tide
Neap TideModerate tidal range
Tidal PatternsSemidiurnal tides- two high and two low per day; Cape Cod, MA (high latitudes)Diurnal tides- one high and one low per day; Mobile, AL (low latitudes)Mixed pattern tides- Two high and two low tides per day BUT with successive high tide levels that are VERY DIFFERENT from each other; Hawaii (mid latitudes)
Type of tide depends on:• Position on the globe• Water depth• Contour- shape of ocean basins
Location of Tide Types World Map
The Bay of Fundy: Site of the world’s largest tidal range
Alma at High Tide Alma at Low Tide
Bay of Fundy
La Rance tidal power plant at St. Malo, France.
Tidal bore = a true tidal wave
• Wall of water that moves upriver
• Caused by an incoming high tide
• Occurs in some low-lying rivers
• Can be large enough to surf or raft
Corals exposed to air at extreme low tide
http://life.bio.sunysb.edu/marinebio/mbweb.html
Tidal Information
HAWAIIAN ISLANDSMean Spring Mean Tide Station Latitude Longitude Range Range Level Predictions SAND ISLAND, MIDWAY ISLANDS 28° 12.7' 177° 21.6' 0.8 1.2 0.6 Predictions
Laysan Island 25° 46' 171° 45' 0.7 1.0 0.4 Predictions East Island, French Frigate Shoals 23° 47' 166° 13' 0.9 1.4 0.6 Predictions Nonopapa, Niihau Island 21° 52' 160° 14' 1.0 1.6 0.7 Predictions
Kauai Island Waimea Bay 21° 57' 159° 40' 1.0 1.6 0.7 Predictions Port Allen, Hanapepe Bay 21° 54' 159° 35' 1.1 1.7 0.7 Predictions NAWILIWILI 21° 57.4' 159° 21.6' Predictions Hanamaulu Bay 22° 00' 159° 20' 0.0 1.2 1.8 Predictions Hanalei Bay 22° 13' 159° 30' 1.3 1.8 0.8 Predictions
Oahu Island Haleiwa, Waialua Bay 21° 36' 158° 07' - - 1.6 0.7 Predictions Waianae 21° 27' 158° 12' 1.2 1.8 0.8 Predictions
HONOLULU 21° 18' 157° 52' 1.3 2.0 0.8 Predictions Hanauma Bay 21° 17' 157° 42' 1.3 1.9 0.8 Predictions Waimanalo 21° 20' 157° 42' 1.1 1.8 0.8 Predictions MOKUOLOE 21° 26.2' 157° 47.6' 1.2 2.0 1.0 Predictions Waikane, Kaneohe Bay 21° 30' 157° 51' 1.4 2.2 1.1 Predictions
Inquiry1.Which has the greatest tidal
effect– sun or moon?2.Where is the greatest tidal
range located?3.Which lunar phase produces
moderate tides?4.How is a tidal bore created?