Friday, February 8 th. Winds/Coriolis Worksheet: Due Today Lab Worksheet: Finish Questions

Transcription

1 Ocean Currents

2 Friday, February 8 th Winds/Coriolis Worksheet: Due Today Lab Worksheet: Finish Questions

3 Non-rotating Earth Convection cell model

4 Add rotation and add landmasses unequal heating and cooling of the Earth

5 Whiteboarding What direction does the wind blow in the United States?

6 Whiteboarding What flight would you expect to take longer: flying from Las Vegas to New York, or New York to Las Vegas?

7 Physical properties of the atmosphere: Density Warm, low density air rises Cool, high density air sinks Creates circularmoving loop of air (convection cell)

8 Physical properties of the atmosphere: Pressure

9 Whiteboarding What type of air pressure exists between the Hadley and Ferrel Cells?

10 90 o High pressure, dry climate 60 o 30 o 0 o 30 o Low pressure, wet climate High pressure, dry climate ITCZ intertropical convergence zone= doldrums Low pressure, wet climate 60 o 90 o

11 The Coriolis effect The Coriolis effect Is a result of Earth s rotation Causes moving objects to follow curved paths: In Northern Hemisphere, curvature is to right In Southern Hemisphere, curvature is to left Changes with latitude: No Coriolis effect at Equator Maximum Coriolis effect at poles

12 The Coriolis effect on Earth As Earth rotates, different latitudes travel at different speeds The change in speed with latitude causes the Coriolis effect

13 Whiteboarding What direction will a plane traveling from Las Vegas to Canada be deflected due to the Coriolis Effect?

14 Whiteboarding What direction will the same plane be deflected on the return flight from Canada to Las Vegas?

15 Whiteboarding Which of the following accurately shows the deflection of a flight due South in the Southern Hemisphere?

16 Monday, February 11 th Grab the Ocean Currents Notes (if you don t have them already) from the front lab table. Copy the objective and work on the warmup. Objective: We will diagram and explain the causes of Surface Currents and Deep Water Currents.

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20 Surface Currents Ocean Currents The upper 400 meters of the ocean (10%). Deep Water Currents Thermal currents (90%)

21 Surface Currents Forces 1. Solar Heating (temp, density) 2. Winds 3. Coriolis

22 Wind-Driven and Density-Driven Currents Wind-driven currents occur in the uppermost 100 m or less Density differences causes by salinity and temperature produce very slow flows in deeper waters.

23 Wind-driven surface currents

24 s/earth_science/terc/content/vis ualizations/es2401/es2401page 01.cfm?chapter_no=visualizatio n

25 Sailors have know about ocean currents for centuries Sailors have know that rivers flow in the seas since ancient times. They used them to shorten voyages, or were delayed by trying to stem them. If navigators do not correct to deflection by currents, they may be far away from where they think they are and meet disaster.

26 Ben Franklin and the Gulf Stream

27 Matthew Fontaine Maury The first systematic study of currents was done by Maury based on logbooks in the US Navy s Depot of Charts and Instruments. His charts and Physical Geography of the Sea assisted navigators worldwide.

28 Winds and surface water Wind blowing over the ocean can move it due to frictional drag. Waves create necessary roughness for wind to couple with water. One rule of thumb holds that wind blowing for 12 hrs at 100 cm per sec will produce a 2 cm per sec current (about 2% of the wind speed)

29 Gyres Water moved by winds is then deflected by the Coriolis Effect, forming Gyres.

30 Current Gyres Gyres are large circular-moving loops of water Five main gyres (one in each ocean basin): North Pacific South Pacific North Atlantic South Atlantic Indian Generally 4 currents in each gyre Centered about 30 o north or south latitude

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32 What do Nike shoes, rubber ducks, and hockey gloves have to do with currents?

33 North Pacific Subtropical Gyre Great Pacific Garbage Patch Estimate: 46,000 pieces of floating garbage/mi 2.

34 North Pacific Subtropical Gyre 135 to 155 W and 35 to 42 N

35 North Pacific Subtropical Gyre Great Pacific Garbage Patch- Good Morning America

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37 Surface and Deep-Sea Current Interactions Giant convection cell circulating around the Earth s oceans. Known as the Global Ocean Conveyor Belt

38 Global ocean circulation that is driven by differences in the density of the sea water which is controlled by temperature and salinity.

39 Deep Water Currents Water freezes at the poles, leaving cold, salty water that has greater density and thus sinks.

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41 Deep Water Currents Water at the equator warms up from the sun and thus has a lower density and rises. Warm surface currents flow towards the poles.

42 Deep Water Currents Results in huge, slow moving, ocean current Just like demonstration in class.

43 White sections represent warm surface currents. Purple sections represent deep cold currents

44 Venn Diagram Complete sentences: One force causing surface currents is or, Both surface currents and deep water currents are affected by Include: Forces that cause them Definitions of each Keywords associated with each (i.e. gyre and thermohaline circulation) Direction of movement

45 Quick Questions 1. What is the primary force causing surface currents?

46 Quick Questions 2. Surface Currents in the Southern Hemisphere rotate.

47 Quick Questions 3. Which of the following comparisons between winds and ocean currents is NOT a good comparison? a. With the exception of the Ferrel Cell, warm air and warm currents flow toward the poles. b. Both are caused by the uneven heating of the Earth s surface. c. Both are affected by the Coriolis Effect. d. Both winds and currents can be caused by differences in salinity.

48 Quick Questions 4. Based on the following picture, garbage dumped off the East Coast in the United states would most likely be found some time later on which of the following continents? a. Australia b. Asia c. Africa d. Antartica

49 El Niño-Southern Oscillation (ENSO) El Niño = warm surface current in equatorial eastern Pacific that occurs periodically around Christmastime Southern Oscillation = change in atmospheric pressure over Pacific Ocean accompanying El Niño ENSO describes a combined oceanicatmospheric disturbance

50 El Niño Oceanic and atmospheric phenomenon in the Pacific Ocean Occurs during December 2 to 7 year cycle Sea Surface Temperature Atmospheric Winds Upwelling

51 Normal conditions in the Pacific Ocean

52 El Niño conditions (ENSO warm phase)

53 La Niña conditions (ENSO cool phase; opposite of El Niño)

54 Non El Niño El Niño 1997

55 Non El Niño upwelling El Niño thermocline

56 El Niño events over the last 55 years El Niño warmings (red) and La Niña coolings (blue) since Source: NOAA Climate Diagnostics Center

57 World Wide Effects of El Niño Weather patterns Marine Life Economic resources El Nino Animation mations/26_ninonina.html

58 Effects of severe El Niños