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## Spring Tide

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**OCEAN SYSTEMS**Geosciences 3220 Spring Tide TIDES Chapter 11 Neap Tide**TIDES - Chapter 11Look For the Following Key Ideas**• Tides are caused by the gravitational attraction of the sun and the moon, by inertia, and by basin resonance. • The Equilibrium Theory of Tides deals primarily with the position and attraction of the Earth, the moon, and the sun. It assumes that the ocean conforms instantly to the forces that affect the position of its surface, and only approximately predicts the behavior of tides. • The Dynamic Theory of Tides takes into account the speed of the long-wavelength tide wave in water of varying depth, the presence of interfering continents, and the circular movement or rhythmic back-and forth rocking of the water in ocean basins. It predicts the behavior of the tides more accurately than the equilibrium theory.**TRUE or FALSE**THE "EQUILIBRIUM THEORY OF TIDES," AS DEVELOPED BY NEWTON, TAKES INTO ACCOUNT THE SHAPE AND DEPTH OF THE GLOBAL OCEAN BASIN**TIDESForces that Generate Tides**• - Tides are caused by the gravitational force of the moon and sun and the motion of earth • Wavelength of tides can be half the circumference • of earth • Tides are the longest of all waves • - Tides are forced waves because they are never free of the forces that cause them**TIDES**Forces that Generate Tides Gravity Will Pull the Planet into the Sun if the Planet Is NOT Moving**TIDES**Forces that Generate Tides Inertia of the Planet Will Keep It Moving in a Straight Line if the Planet is Moving**TIDES**Forces that Generate Tides Earth – Moon – Sun System**TIDES**Forces that Generate Tides Gravity and Inertia Together Cause the Planet to Travel a Fixed Path Around the Sun in a Stable Orbit**TIDES**Forces that Generate Tides Earth – Moon – Sun System**TIDES**Equilibrium Theory of Tides Moon and Tractive Forces The moon does not rotate around the center of the Earth. Earth and the moon together - the Earth-moon System - rotate around a common center of mass about 1,650 km (1,023 mi) beneath the Earth’s surface**TIDES**Forces that Generate Tides Earth – Moon – Sun System**TRUE or FALSE**THE SUN EXERTS THE MOST INFLUENCE ON EARTH'S TIDE BECAUSE IT IS THE LARGEST BODY IN THE "EARTH, MOON, SUN SYSTEM"**TIDES**Equilibrium Theory of Tides Moon and Tractive Forces The moon’s gravity attracts the ocean toward it**TIDES**Equilibrium Theory of Tides Moon and Tractive Forces Motion of Earth around the center of mass of the Earth-moon System throws up a bulge on the side of the Earth opposite the moon**TIDES**Equilibrium Theory of Tides Moon and Tractive Forces Combination of the two effects creates two tidal bulges**TIDES**Equilibrium Theory of Tides Moon and Tractive Forces**TIDES**Forces that Generate Tides The Lunar Day The Lunar Day is the time that elapses between when the moon is directly overhead and the next time the moon is directly overhead. During one complete rotation of Earth (24 hour solar day) the moon moves eastward 12.2 degrees, and Earth must rotate an additional 50 minutes to place the moon in the exact same position overhead. Thus, the lunar day is 24 hours 50 minutes long.**Tidal Bulges Follow the Moon**TIDES Equilibrium Theory of Tides Moon and Tractive Forces**TIDES**Equilibrium Theory of Tides Moon and Tractive Forces**TIDES**Spring and Neap Tides**TIDES - The Dynamic Theory of Tides**Explains the characteristics of ocean tides based on celestial mechanics (the gravity of the sun and moon acting on Earth) and the characteristics of fluid motion Tidal Patterns Semidiurnal, Diurnal, Mixed Tides Twice each lunar day Once each lunar day Different tidal heights**TIDESThe Dynamic Theory of Tides Global**PatternsSemidiurnal, Diurnal, Mixed Tides**TIDES**The Dynamic Theory of Tides Amphidromic Points**TIDES**The Dynamic Theory of Tides Amphidromic Points – Global Pattern Blue = least tidal height, Red = most tidal height**TIDESThe Dynamic Theory of TidesAmphidromic Points -Confined**Basins Theoretical Broad, Shallow Basin Gulf of St. Lawrence, Southeastern Canada**TIDESThe Dynamic Theory of TidesAmphidromic Points -Confined**Basins Bay Waters Resonate (Seiches) at Same Frequency as Lunar Tide Tides in a narrow basin Amphidromic System Does Not Develop - Space for Rotation Is Not Available**TIDES**Tidal Range Eastern Bay of Fundy Atlantic Coast, Canada Tidal Range > 15 m (50’) Water Rises 1 m (3.3’) in 23 minutes at flood peak**TIDES**Tidal Range Eastern Bay of Fundy Near St. John, New Brunswick Atlantic Coast, Canada Other Places with Large Tides: 10 m (33’) Range Port of Bristol, England Sea of Okhotsk, NE Japan Turnagain Arm, Alaska Bay of St. Malo, France Feuilles River - Ungava Bay, Quebec**TRUE or FALSE**THERE ARE NUMEROUS AMPHIDROMIC POINTS LOCATED THROUGHOUT THE GLOBAL OCEAN**TIDES**The Dynamic Theory of Tides Amphidromic Points – Global Pattern Blue = least tidal height, Red = most tidal height**TIDES**Tides in Confined Basins Tidal Bore Bay of Fundy Tidal Range of 15-20 m (45-75 ft.)**TIDES**Tides in Confined Basins Tidal Bore Qiantang River, China - World’s Largest Tidal Bore**Maelstrom**Straits Between Norwegian Islands of Moskenes and Moskenesoya**TIDESMarineOrganisms**Tides have a profound affect on coastal marine life Coastal life is sorted into zones and subzones, depending on the amount of emergence and submergence the organisms can tolerate**Grunion Run**Grunion (genus Leuresthes) swim ashore at night just after highest spring tide Eggs hatch 2 weeks later when spring tide returns**LaRance Estuary,**St. Malo, France - 24 generating units - 10 million watts each - Each serves over 1500 homes for a year TIDESTide Generated Electricity Surface Area = 23 km2 (9mi2) Max Tidal Range = 13.4 m (44’) Deepest Water: 12 m (39’) at low tide 25 m (82’) at high tide Barrier 3 km (2 mi) Upstream Estuary 760 m (12500’) Wide at Barrier Open Ocean**TRUE or FALSE**COASTLINES SUBJECTED TO DIURNAL TIDES WOULD BE THE BEST AREAS TO LOCATE "TIDAL ELECTRICAL GENERATING STRUCTURES"**TIDES - The Dynamic Theory of Tides**Explains the characteristics of ocean tides based on celestial mechanics (the gravity of the sun and moon acting on Earth) and the characteristics of fluid motion Tidal Patterns Semidiurnal, Diurnal, Mixed Tides Twice each lunar day Once each lunar day Different tidal heights**TIDESThe Dynamic Theory of Tides Global**PatternsSemidiurnal, Diurnal, Mixed Tides**OCEAN SYSTEMS**Geosciences 3220 Spring Tide TIDES Chapter 11 Neap Tide