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waves and tides
Waves and tides are caused by the gravitational pull of the moon and sun. There are different types of waves including wind waves and tsunamis. Tides are the regular rising and falling of ocean water levels caused by lunar and solar gravitational forces. High tides occur when the gravitational pulls act in alignment and low tides occur when they are perpendicular. Tides are important because they allow for shipping in harbors and prevent freezing in cold weather ports.
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waves and tides
- 1. PRESENTED BY UNDERGUIDANCE OF PRAMODA G DR. BALASUBRAMANIAN A 1ST SEMESTER, PROFESSOR APPLIED GEOLOGY Presentation on OCEAN WAVES AND TIDES
- 2. CONTENTS • Introduction • Waves •Types of waves • Tsunamis • Tides • Types of tides • Importance of tides • Conclusion • Reference
- 3. INTRODUCTION • A waveis any disturbance created when energy moves through an object or substance. • There are many types of waves caused by different forces – some examples are earthquakes, ocean waves, radio waves, visible light waves, and atmospheric waves. • Tide, alternate and regular rise and fall of sea level in oceans and other large bodies of water. • These changes are caused by the gravitational attraction of the moon and, to a lesser extent, of the sun on the earth.
- 4. • A disturbance onthe surface of water, caused by the rhythmic movement of water particles due to the action of winds. • The height of the wave depends on the speed of the wind. • A tsunami is a very long wave caused by submarine or coastal earthquakes, landslide or volcanic eruption. WAVES
- 5. WAVE CHARACTERISTICS Parts of aWave Crest = high point Trough = low point Height = vertical distance a from crest to trough Wavelength = Horizontal distance between crest to crest or trough to trough
- 6. Wave period :time for 2 crests to pass fixed point (T) sec Wave speed (C) : C = wavelength / T (m/s) Wave steepness : H / wavelength When H / wavelength = 1/7 or angle at crest 120 or less = Breaker
- 7. SIZE OF WINDGENERATED WAVES Depends on 3 things: Wind Speed Wind Duration (length of time wind blows) “Fetch” Extent of open water across which the wind can blow
- 8. WATER MOTION INWAVES Water travels in vertical circular orbits Wave moves, particles don’t!
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- 10. Tsunami Waves Caused byundersea quake or volcano Wavelength = ~150 mi. Wave height = 6” – 1’ Can NOT perceive in boat Speed > 500 mph lows down to ~25 mph at shore; water builds up to ~65+ ft A tsunami also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake.
- 12. IMPORTANCE OF WAVES Shaping Coastlines Erode cliffs Grind rock into sand Ecology Returns O2 to water Stir up food for filter feeders
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- 14. • Are thealternate rise and fall in the level of sea water, caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.
- 15. • High Tideis when the level of sea water rises, and moves up the shore. • Low tide is when the level of sea water falls and water recedes from the shore. • Most coastal areas experience two high and two low tides per day.
- 17. • Is causedwhen the pulls of the moon and sun act on the same line during full moon and new moon • High tides are higher than usual and low tides lower
- 18. • Is causedwhen the moon is in the first or third quarter,when the moon,sun and earth form a right angle • The height of the tide produced by the moon's attraction is reduced by the sun's attraction • High tides are not as high as usual and low tides not as low
- 20. SPRING TIDES ANDNEAP TIDES The Bay of Fundy at high tide The Bay of Fundy at low tide
- 21. HOW ARE TIDESUSEFUL? The rise in water during high tide allows big ships to enter or leave harbors safely. During high tide, water rushes up the mouths of rivers. This helps ships to move in and out of river ports. The saline waters of the sea freeze at a lower temperature than river water does. In cold countries, the sea water rushing in during high tide prevents harbors from freezing in winter.
- 22. CONCLUSION • Wind wavesare the most common type of wave in the ocean and are found superimposed on currents, tides, and tsunami. • There are different types of waves they can classified depending upon velocity of waves. • The wind transfers some of its energy to the water, through friction between the air molecules and the water molecules. Stronger winds (like storm surges) cause larger waves. • Tides are play major role in the sea or ocean transport. • The water in the ocean tides moves back and forth and these mass redistributions cause periodic loading of the ocean bottom
- 23. REFERENCE • Oceans andOceanography By John P. Rafferty – 2011 • Waves, Tides, and Shallow-water Processes by John Wright, Angela Colling, Dave Park, Open University. Oceanography Course Team 1999. • www.googleimages.com • www.Wikipedia.com
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