1. Unit 4- Physical Oceanography

2. Currents
Ocean current- mass of ocean water that flows from one place to another
Two types
Surface/wind-driven
Deep/density-driven

4. Coriolis Effect
Coriolis Effect- a “deflection” of a moving object due to the fact that the Earth is rotating
Moving object travels in straight line from outside reference, but Earth has moved underneath, so object appears to move in a curved path
Objects are deflected to the RIGHT in the Northern Hemisphere and to the LEFT in the Southern Hemisphere
No effect at the Equator and maximum effect at the poles

6. Global Winds Winds named based on where they are coming from
Northern Hemisphere winds:
Polar Easteries
Prevailing Westerlies
NE Trade Winds
Southern Hemisphere winds:
Polar Easterlies
SE Trade Winds

8. Waves Three main causes of ocean waves 1. Wind* 2. Tides
3. Seismic Activity (earthquakes, volcanoes)

9. Waves Other factors affecting wave height Distance from shoreline
Latitude
Water depth
Nearby landmasses

10. Wave Energy

11. Tides
Definition – low, earth-wide waves that cause regular rise/fall in sea level
Take place every 12 hours and 25 minutes; therefore, they are predictable
Vary in height (from 1-20 meters)

13. Causes of Tides 1. Gravity
Moon pulls water towards it, creates bulge on moon side of earth
Sun- same thing, but only about 1/3 – 1/2 the effect; responsible for extra high tides

14. Causes of Tides 2. Inertia (centripetal force)
Things want to keep moving in straight line
“Counteracts” the force of gravity from moon
Causes opposite bulge on far side of earth

15. Two high tides & two low tides per day
Time of high/low tide depends on the lunar cycle

16. Types of Tides
Flood- when tide is coming in (change from a low to high tide)
Ebb- when tide is going out (change from a high to low tide)

17. Types of Tides
Spring- very strong tides, due to alignment of Earth, sun, and moon (straight line)
Neap- very weak tides, due to alignment of Earth, sun, and moon at 90° angle (effects cancel)

18. When would spring tides occur? When would neap tides occur?
Lunar Cycle days
When would spring tides occur? When would neap tides occur?

19. Lunar Cycle & Tides Spring tides- new moon and full moon
Neap tides- 1st quarter moon and 3rd quarter moon
Spring & Neap occur once every 14 days

20. http://oceanservice. noaa

21. Tidal Bore
Tidal bore occurs when a river runs backwards due to incoming tide and land formation around it

22. Importance of Tides Mix shallow waters
Move floating organisms into/from breeding areas
Fisheries, ships, recreation

24. Tsunamis
Tsunami- underwater seismic activity that transfers lots of energy into a water column
Ex.- Earthquakes, volcanoes, avalanches
Drawback- trough of wave reaches shore before the crest, so water along the shoreline recedes dramatically
Waves slow down as they reach the shore, increasing in height

25. Tsunamis: Coastal Impacts
Not a huge breaking wave, rather a strong flood
Extreme destruction
Marine life washed ashore
Often injuries and casualties

28. ENSO Cycle ENSO (stands for El Niño/ Southern Oscillation) Cycle:
Year-to-year variations in temperature, rainfall, air pressure, circulation, etc.
Occurs in the equatorial Pacific
Highly irregular pattern
The cycle can last anywhere from 2-10 years

29. El Niño
Refers to the above average sea-surface temperatures that periodically develop across the east-central equatorial Pacific
Represents the warm phase of the ENSO cycle
Cause: equatorial easterly trade winds diminish, resulting in an eastward shift of the Pacific warm pool

30. How El Niño Affects Global Climate
Warmer winters across the northern U.S.
Gulf states cooler and wetter
Increases storms on the west coast of North & South Americas
Fisheries disrupted
Can cause a drought in Indonesia and western Pacific

31. La Niña Periodic cooling of sea-surface temperatures
East-central equatorial Pacific
Represents the cold phase of the ENSO cycle
Equatorial easterly trade winds strengthen

32. How La Niña Affects Global Climate
La Niña has equally dramatic, often opposite effects of El Niño
Could increase the number of Atlantic hurricanes
Where there was drought, now turns to flooding; flooding turns to drought
Abnormally mild winter now turn to abnormally harsh winter

33. 2011 La Niña Major snowfall Extreme flooding/high river levels
Severe drought in Southwest
Joplin/Tuscaloosa tornados
Warmer temperatures in the fall

34. Tropical Cyclone Huge rotating masses of low pressure
Generate strong winds and torrential rain
Called hurricanes in North and South America
Called typhoons in Pacific
Called cyclones in Indian Ocean

35. Hurricane Conditions Warm ocean water Warm moist air
Coriolis Effect- causes hurricanes to spin
Found during late summer and early fall
Hurricane season: June 1- November 30

36. Hurricane Movement Driven by trade winds
Move east to west across oceans
Eye of the hurricane- winds are drawn upward, so horizontal wind speeds are low= usually calm
Composed of spiral rain bands that create intense rainfall
Movement over land cuts off energy source

37. Hurricane Destruction
Caused by high winds and flooding from intense rainfall
Storm surge- extremely high winds cause water to pile up higher than normal sea level
Main cause of destruction

38. Tropical Cyclone Destruction
Deadliest Storm:
Great Bhola Cyclone- 1970, Bangladesh killed 500,000 people
Top 30 deadliest tropical storms all occurred in Indian Ocean or western Pacific near China

39. U.S. Hurricanes Deadliest: Most damaging:
1. Galveston Hurricane in Galveston, TX killed over 6,000 people
Deadliest natural disaster in US history
3. Hurricane Katrina deaths
Most damaging:
Hurricane Katrina- 2005, caused over $100 billion in damage
Hurricane Sandy- 2012, caused $50 billion in damage