TIDES

1. TIDES Janek, Ivy, Jessica, Ye Chan, Kelvin

2. Tides-What are they? • Tides are daily changes in the level of ocean water • Tides are the periodic rise and fall of the water level in the oceans and other large bodies of water

3. Tides are generated by: • 1) Gravitational Pull of the Moon and Sun • 2) Centripetal Force of the rotating Earth (Centrifugal, the opposite way) • Wind, Earthquakes and plate tectonics also move ocean water but the dominant force is gravitational

4. Gravitational Pull (Moon & Sun) • Moon has 2x greater gravitational pull than the sun • Sun is 10 million times more massive than the moon but is also 390x farther away

5. Centripetal Force

7. Isaac Newton • Newton’s Universal Gravitation theory helped to explain how the gravity of the moon (and the sun) were related to tides.

8. Tidal Cycles • Mixed Tide: 12hr 25min cycle • Diurnal Tide: 24hr 50min cycle • Semi Diurnal Tide: 12hr 25min cycle

9. Description of tides • High Water: a water level maximum (high tide) • Low Water: a water level minimum (low tide) • Tidal range: the difference between low and high tide • Spring Tide: full moon and new moon (14.77 days) • Neap Tide: 1st quarter and 3rd quarter (14.77 days) Intertidal zone High tide Low tide

10. Bay of Fundy High Tide Low Tide

11. The Monthly Tidal Cycle (29.5 days) 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

12. Tidal Patterns • Semidiurnal tides- two high and two low per day • Diurnal tides- one high and one low per day • Mixed Pattern tides- two high and two low tides per day but with successive high tide levels are very different from each other; ex. Hawaii Type of tide depends on: • Position on the globe • Water Depth • Contour- shape of ocean Basins

13. Location of Tide Types (World)

14. Importance of Intertidal Zones • Many organisms depend on the abundance of food regularly washed in the intertidal zones. • This region is an important modal system for the study of ecology.

15. Tidal Bore 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

16. Causes of Sea Levels Rising • Global Mean Sea Level (GMSL) has risen by 10 to 20 centimeters. • The annual rate of rise over the past 20 years has been 3.2 millimeters a year. 

17. Three primary factors • Global Warming • Thermal Expansion • Melting of Glaciers and Polar Ice Caps

18. Global Warming • Burning of fossil fuels • Human and Natural activities • Deforestation

20. Thermal Expansion • When water heats up, it expands.

21. Melting of Glaciers and Polar Ice Caps • Large ice formations, like glaciers and the polar ice caps, naturally melt back a bit each summer. • During winter, snow generated primarily from evaporated seawater, are generally sufficient to balance out the melting.

23. Higher temperatures caused by global warming have led to greater-than-average summer melting and diminished snowfall due to later winters and earlier springs.

24. This imbalance results in a significant net gain in runoff versus evaporation for the ocean, causing sea levels to rise. 

25. Consequences • Devastating effects on coastal habitats. • Destructive erosion • flooding of wetlands • contamination of aquifers and agricultural soils. 

27. When large storms hit land, higher sea levels mean bigger and more powerful storms. 

28. Local areas become increasingly vulnerable to flooding. • Force civilians to abandon the area. • Low-lying islands submerged completely. 

29. Questions Short Answer • How is tidal bore created? • What is the difference in levels of ocean water at high tide and low tide called? Multiple Choice 1. Which has the greatest tidal effect? • Sun b) moon c) earthquakes d) wind 2. Type of tide depends on? a) Position on the globe b)Water Depth c) Contour shape of ocean Basins d) all of the above

30. 3. All of these are characteristics of Neap Tides except for? a)Earth-Moon-Sun system at right angles b) Lunar and solar bulges destructively interfere c) large Tidal Range d) Cycle occurs every 7 days 4. When Water levels are at a minimum this is called? • Low water b) high water c) tidal range d) spring tide 5. Which of the following is not part of the tidal cycle • Mixed Tide b) Semi Mixed c) Diurnal Tide d) Semi Diurnal 6. The moon has a gravitational pull… (in comparison to the sun) • 0.2x stronger b) 0.5x stronger c) equal to d) 2x stronger 7. The Coast of Vancouver Island Incurs tides that are… a) Mixed b) Diurnal c) Semi Mixed d) Semi Diurnal

31. Critical Question • How are tides affected by the rise of sea levels increasing due to: global warming, thermal expansion and melting of glaciers? What are the consequences of a sudden or even gradual change in the tidal cycles across the globe?

32. BIBLIOGRAPHY WEBSITES http://omp.gso.uri.edu/ompweb/doee/science/biology/inter1.htm http://www.marees.gc.ca/eng/find/zone/4 http://science.howstuffworks.com/environmental/earth/geophysics/tide-cause.htm http://www.moonconnection.com/tides.phtml http://www.enchantedlearning.com/biomes/intertidal/intertidal.shtml http://ocean.nationalgeographic.com/ocean/critical-issues-sea-level-rise/ http://www3.telus.net/subductionservices/sealevels.htm IMAGES http://scientopia.org/blogs/galacticinteractions/2011/01/22/one-slide-explanation-of-tides/ http://en.wikipedia.org/wiki/Tide Video http://www.youtube.com/watch?v=EnDJ6_XpGfo

33. Answers to quiz SA 1) a tidal wave 2)Tidal Range MC 1) B 2) D 3) C 4) A 5) B 6) D 7) A