Presentation on theme: "The Reality of Sending a Message in a Bottle"— Presentation transcript:
1The Reality of Sending a Message in a Bottle Ocean CurrentsThe Reality of Sending a Message in a Bottle
2? Why does the Ocean have waves? What are the parts of a wave? How does water move in a wave?What happens when a wave hits a beach?
3Define wave:Wave – a rhythmic movement that carries energy through matter or space.in the ocean, waves move through seawater.
4Parts of a waveWave heightWavelengthCrestCrestTrough
5Parts of a wave: Crest – the highest part of a wave. Trough – the lowest part of a wave.Wavelength – the distance between two adjacent crests.Wave height – the vertical distance between the lowest part and the highest part.
6More wave wordsFrequency – the number of complete waves (or oscillations) that occur over a given period of time. Usually measured in cycles per second.Amplitude – half the wave height
7Most waves caused by wind Friction from the wind moving over the water causes the water to move along with the wind.If the wind speed is high enough, the water begins to pile up and a wave is formed.
8How does water move in a wave? Some clues:When you were at the beach, you probably noticed that the edge of the water goes back and forth with the waves.If you float an object on the ocean, it stays roughly in one place. It is not pushed forward by the waves.
9How water moves in a wave: Particles of water move around in circles The farther below the surface, the smaller the circle.At a depth about equal to half the wavelength, the motion stops.
10At the beach:Wavelength decrease and wave height increases as waves approach the shore.ConstantWavelengthWaves drag against the bottomand wave length decreases
11At the beach, part 2As the wave slows, its crest and trough come closer together. The top of the wave is not slowed by friction and moves faster than the bottom.The top of the wave outruns the bottom and falls over. This collapsing wave is called a breaker.
12Ocean Current LayersSurface Currents – upper 10% of the ocean; upper 400 mPycnocline – the layer between surface and deep waters; where a rapid change in temperature, salinity and density occurDeep Current – lower 90% of the ocean
13Ocean Water Properties How they impact ocean currentsTemperature – remember heat rises!Salinity – remember salty water sinks!Density – a function of temperature and salinity
18Primary Current Forces These Start the Water MOVING:Solar HeatingWindsGravityCoriolis Force/Effect
19Current Forces Explained Sun/solar heating - causes water to expand and moveWinds - push the water; winds blowing for 10 hrs across ocean will cause the surface water to ~2% wind speed; wind has the greatest effect on surface currentsGravity - pull water downhill or pile against the pressure gradient (high/low); influences tides
22Current Influences (cont’d) Coriolis effect/force - Force due to the Earth's rotation, capable of generating currents. It causes moving bodies to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. The "force" is proportional to the speed and latitude of the moving object. It is zero at the equator and maximum at the polescauses the water to move around the mound of water
23Surface CurrentsSurface current – with surface circulation is less dense and influenced by windsWarm surface currents: wind and Earth’s rotationCold surface currents: flow towards the equatorUpwelling current: cold, nutrient rich; result of windWestern Boundary currents: warm & fastEastern Boundary currents: broad, slow, cool & shallow, associated with upwellingEx: Gulf Stream = surface current that is the upper 20% of the ocean, western boundary current
24Deep CurrentsDeep water – cold, dense, salty; move by density forces and gravity; move slower than layers aboveThermohaline Circulation: is global ocean circulation. It is driven by differences in the density of the sea water which is controlled by temperature (thermal) and salinity (haline). In the North Atlantic it transports warm and salty water to the North. There the water is cooled and sinks into the deep ocean. This newly formed deep water is subsequently exported southward. This slow (~0.1 m/s), but giant circulation has a flow equal to about 100 Amazon Rivers. Together with the Gulf Stream it contributes to the comparatively warm sea surface temperature along the coast of western Europe and to the relative mild European winters. Once the water are in the deep, they remain there for up to 1000 years.Ex: Global Conveyer Belt = deep current that is the lower 20% of the ocean; takes 1,000 years to complete the cycle
25Graphic - http://www.grida.no/climate/vital/32.htm Global Conveyer BeltThermohaline circulation links the Earth's oceans. Cold, dense, salty water from the North Atlantic sinks into the deep and drives the circulation like a giant plunger.Graphic -
26Other CurrentsGyres – large mounds of water; large circular currents in the ocean basinEx: North Atlantic Gyre = consists of 4 separate currents – N. Equatorial, Gulf Stream, N. Atlantic Drift and Canary Currents
27Ocean Currents & Living Things Currents are important to marine life as they help move food and nutrients making them available for photosynthesis, metabolic requirements and or consumption.
28OCEAN Motion Foldable (2 Tab Foldable) Take your sheet of copy paper and fold it “Hamburger” styleThen fold the paper again “Hamberger” styleLook at my paper to make sure you’ve done it correctly before cutting.
294. Cut only the top sheet of paper at the fold line (creating 2 flaps covering the back of paper) Look at my example.Write Title on top flap“Causes of Ocean Motion”Write Title on other top flap“Effects of Ocean Motion”
30Under “Causes” Flap write 2 causes for each type of motion. USE PGS Under “Causes” Flap write 2 causes for each type of motion ****USE PGS TO HELPCurrentsWaves
31Under “Effects” flap Write at least 2 effects of the 4 different types of Ocean Motion Surface Current:Density Currents:Waves:Tides:****USE PGS TO HELP
32Parts of a waveWave heightWavelengthCrestCrestTrough