© 2006 Thomson-Brooks Cole Chapter 4 Water, Waves, and Tides

© 2006 Thomson-Brooks Cole Atom The smallest particle an element can be divided into & maintain properties Building block of matter

© 2006 Thomson-Brooks Cole Molecule A group of atoms chemically combined that can exist by itself CO 2

© 2006 Thomson-Brooks Cole Ion Charged particle Cl -1

© 2006 Thomson-Brooks Cole Polyatomic Ion A group of atoms chemically combined that together have a charge CO 3 -2

© 2006 Thomson-Brooks Cole Bond A strong attraction between atoms that hold compounds together Ionic, covalent & metallic

© 2006 Thomson-Brooks Cole Key Concepts The polar nature of water accounts for many of its physical properties. Seawater contains a number of salts, the most abundant being sodium chloride. Salts are constantly being added to and removed from the oceans. The exchange of energy between oceans and the atmosphere produces winds that drive ocean currents and weather patterns.

© 2006 Thomson-Brooks Cole Key Concepts The density of seawater is mainly determined by temperature and salinity. Vertical mixing of seawater carries oxygen to the deep and nutrients to the surface. Waves are the result of forces acting on the surface of the water. The gravitational pull of the moon and the sun on the oceans produces tides.

© 2006 Thomson-Brooks Cole

Nature of Water Physical properties of water –excellent solvent –high boiling point and freezing point –denser in its liquid form than in its solid form –supports marine organisms through buoyancy –provides a medium for chemical reactions necessary for life

© 2006 Thomson-Brooks Cole Nature of Water Structure of a water molecule –2 H atoms bonded to 1 O atom –polar—different parts of the molecule have different electrical charges

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Nature of Water Freezing point and boiling point –hydrogen bonds—weak attractive forces between slightly positive H atoms of one molecule and slightly negative O ends of nearby molecules –responsible for high freezing/boiling points

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Nature of Water Water as a solvent –polar nature keeps solute’s ions in solution –water cannot dissolve non-polar molecules

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Nature of Water Cohesion, adhesion, and capillary action –cohesive H bonds = high surface tension –adhesion—attraction of water to surfaces of objects that carry electrical charges, which allows it to make things wet –capillary action—the ability of water to rise in narrow spaces, owing to adhesion

© 2006 Thomson-Brooks Cole

Nature of Water Specific heat –water has a high specific heat (amount of heat energy needed to raise 1 g 1 o C) –ocean can maintain relatively constant temperature Water and light –much light reflected into the atmosphere –different wavelengths (colors) of light penetrate to different depths

© 2006 Thomson-Brooks Cole Nature of Water Chemical properties of water –acids release H + atoms in water –bases bind H ions and remove them from solution –pH scale measures acidity/alkalinity –ocean’s pH is slightly alkaline (average 8) owing to bicarbonate and carbonate ions –organisms’ internal and external pH affect life processes such as metabolism and growth

© 2006 Thomson-Brooks Cole

Salt Water Composition of seawater –6 ions make up 99% of dissolved salts in the ocean: sodium (Na + ) magnesium (Mg 2+ ) calcium (Ca 2+ ) potassium (K + ) chloride (Cl - ) sulfate (SO 4 2- ) –trace elements—present in concentrations of less than 1 part per million

© 2006 Thomson-Brooks Cole

Salt Water Salinity –seawater = 3.5% salt, 96.5% water –expressed as in g per kg water or parts per thousand –salinity of surface water varies as a result of evaporation, precipitation, freezing, thawing, and freshwater runoff from land –10 o N-10 o S = low salinity (heavy rainfall) –areas around 30 o N and 30 o S = high salinity (evaporation) –from 50 o = low salinity (heavy rainfall) –poles = high salinity (freezing)

© 2006 Thomson-Brooks Cole

Salt Water Cycling of sea salts –sea salt originally from earth’s crust –ocean composition has remained the same owing to balance between addition through runoff and removal –salts removed in many ways: sinking or depositing on land by sea spray evaporites concentration in tissues of organisms harvested for food adsorption—process of ions sticking to surface of fine particles, which sink into sediments

© 2006 Thomson-Brooks Cole

Salt Water Gases in seawater –gases from biological processes oxygen is a by-product of photosynthesis most organisms use O, release CO 2 just below sunlit surface waters is the oxygen- minimum zone –solubility of gases in seawater seawater has more O and CO 2 but less N than the atmosphere solubility: CO 2 > O > N affected by temperature, salinity and pressure

© 2006 Thomson-Brooks Cole Coriolis Effect Due to the rotation of the Earth, fluids tend to veer to form cyclic patterns

© 2006 Thomson-Brooks Cole Northern Hemisphere: Water veers right to make clockwise cycles Southern Hemisphere: Water veers left to make counter- clockwise cycles

© 2006 Thomson-Brooks Cole Convection Currents Fluids form cyclic flowing patterns due to heat differences Warm air rises & displaces cooler air which drops

© 2006 Thomson-Brooks Cole All of the Earth’s weather patterns are caused by convection currents and the Coriolis Effect

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Trade Winds Winds that tend to blow in the same direction all the time Easterlies: wind from east

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Gyres Ocean-wide cyclic surface circulation patterns caused by wind friction & Coriolis Effect

© 2006 Thomson-Brooks Cole Oceanic Gyres Huge clockwise cycles in the northern hemisphere Huge counter- clockwise cycles in the south

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Waves A form of energy transfer Crest: highest point Trough: lowest point

© 2006 Thomson-Brooks Cole Wavelength The distance between corresponding points Crest to crest

© 2006 Thomson-Brooks Cole Period The time it takes for one wave to pass

© 2006 Thomson-Brooks Cole Surface Wave The recognizable wave we see in the ocean Caused by wind

© 2006 Thomson-Brooks Cole Wave Height Determined by wind speed, fetch, and wave reinforcement

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Fetch The distance in which winds flow over the water in the same direction

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Wave Reinforcement When the crests of two or more waves flow simultaneously the height of the wave would be the addition of the two

© 2006 Thomson-Brooks Cole Seismic Waves Waves caused by geological activity (earthquakes) Tsunamis Tidal waves

© 2006 Thomson-Brooks Cole Tides Rhythmic pattern of the rising & falling of the water level in the ocean

© 2006 Thomson-Brooks Cole Cause of Tides Gravitational pull of the moon on the Earth Gravitational pull of the sun on the Earth Spinning of the Earth

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Tidal Range The vertical distance between the highest and lowest tides

© 2006 Thomson-Brooks Cole Spring Tides Greatest tidal range Occurs when the sun, moon, & Earth are alligned

© 2006 Thomson-Brooks Cole Neap Tides Smallest tidal range Occurs when the sun & the moon are at right angles from Earth

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Diurnal Tides One tide cycle per day

© 2006 Thomson-Brooks Cole Semidiurnal Tides Two tide cycles per day Occurs most often

© 2006 Thomson-Brooks Cole Overturn When surface and deep water switch places Caused by sudden cooling with increasing density

© 2006 Thomson-Brooks Cole Ocean Layers Surface water Intermediate water at the main thermocline Deep water

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Deepwater Circulation Patterns Upwellings near the equator Downwellings near the poles Creating large slow convection currents

© 2006 Thomson-Brooks Cole Upwelling When deep water comes to the surface