2.  A. The Unique Nature of Pure Water  All matter is made of atoms  Elements are make from one kind of atom  A molecule is two or more different atoms combined  Water is a polar molecule; one end is positively charged and the other is negatively charged  Draw Molecule

3.  Only substance on Earth to naturally exist in three states  Weak hydrogen bonds form between to the positive end and the negative end of different water molecules  Solid water molecules pack close together & locked in fixed three dimensional pattern  Becomes more dense until about 4°C (get less dense) & expands (this is why ice floats!)  When water freezes in fresh and marine water the ice forms on top allowing organisms to live underneath the ice  When marine water freezes it acts like an insulator to stop freezing all the water

4.  Bonds must be broken before molecules can begin to move around  Melts at higher temperature & absorbs a lot of heat when it melts (high latent heart of melting)

5.  Melting ice, added heat breaks more hydrogen bonds than increasing molecular motion  Mixture of ice & water is 0°-adding heat goes into melting the ice not raising temperature  High heat capacity therefore marine organisms not affect by temperature changes in atmosphere & latent heat of evaporation

6.  Dissolve more things than any other natural substance  (universal solvent) especially salts  Salts made of opposite charged particles and conducts electricity  Single atoms or groups of atoms  In water, strong ion charges attract water molecule, water molecules surround the ions and pull them apart (dissociation)

7.  Characteristics due to nature of pure water & materials dissolved in it  Dissolved solids due to chemical weathering of rocks on land & hydrothermal vents

8.  1. Salt Composition  Sodium chloride account for 85% of all solids dissolved  Salinity is total salt dissolved in seawater (number of grams left behind when 1000 grams evaporated)  if 35 grams left then 35 parts per thousand or 350/00 or 35 psu (practical salinity units)

9.  Rule of constant proportions states that the relative amounts of various ions in seawater are always the same  Differences in salinity results from removal (evaporation) and addition (precipitation) of water  Rarely have to deal with changes in ratio of ions as result easier to control salt & water balance  Average salinity is 35 psu and between 33-37 psu in open ocean  Red Sea is 40 psu & Baltic Sea is 7 psu  Why is Red Sea salinity so high and the Baltic Sea so low?

10.  Get denser as it gets saltier, colder, or both  -2° to 30°C temps. below zero possible because saltwater freezes at colder temps.  Density controlled more by temperature than salinity  There are exceptions therefore salinity & temp need to be measured to determine density

11.  O2, CO2 and N2 in atmosphere & sea surface  Gas exchange happens between the surface & atmosphere  Dissolved gas concentration higher in cold water, lower in warm water  Amount of oxygen in water is affected by photosynthesis & respiration  Most oxygen is released into the atmosphere  More susceptible to oxygen depletion than atmosphere  80% of gasses is carbon dioxide

12.  Sunlight can penetrate, but it’s affected by the material suspended in the water  Important to the photosynthetic organisms  Runoff makes coastal waters less transparent

13.  On land, organisms are under 1 atm at sea level  Marine organism have the pressure of the atmosphere & water  With every 10m increase depth another atm is added  As atms increase gases are compressed  Organism have air bladders, floats and lungs that shrink and collapse  Limits depth range, some organism are injured when brought to the surface  Submarines & housing must be specially engineered to withstand pressure

15.  Throughout depths currents move and mix ocean waters and transport heat, nutrients, pollutants and organisms

16.  Driven by the wind

17.  Because Earth is rotating anything that moves over the surface tends to turn a little rather than in a straight line  Deflects large-scale motions like winds and currents to the right in Northern Hemisphere and to the left in Southern Hemisphere https://www.youtube.com/watch?v=rdGtcZSFR Lk

18.  Winds driven by heat energy from sun  Trade winds  warmer at equator  wind at equator becomes less dense and air from adjacent areas gets sucked in to replace it creating winds  wind bent by Coriolis Effect  approach equator at 45° angle where there is no land  steadiest winds  Westerlies at middle latitudes move in opposite direction  Polar easterlies at high latitudes

20.  Winds push the sea surface creating currents  Ekman spiral-Surface current moves off 45°   Top layer pushes on layer below & again Second layer moves slightly to right and slower and is repeated down the water column  lower waters move progressively at greater angles from wind  Effect of wind decreases with depth  currents combine into huge gyres (large systems of circulating currents

22.  west side of gyres carry warm water to higher latitudes while cold current flow on eastern sides  giant thermostat warming the poles & cooling  tropics  tropical organisms like corals tend to extend into high latitudes on the west sides of the oceans  cold loving organisms like kelp grow closest to equator on eastern shores

23.  large-scale fluctuations can cause conditions like El Nino  current shift with season and weather  near the continental shelf currents are effected by the shape of the bottom & coastline

24.  Circulation and the Great Ocean Conveyor  Ocean water stratified  Cold more dense on the bottom & warmer less dense on top

25.  Surface layer or mixed layer 100 to 200m thick  Mixed by wind, waves and currents  Sometimes in summer & spring in temperate & polar waters sharp transition to cooler  water (theromoclines) noticed by divers -Change in temp as you get deeper  Intermediate layer depth of 1000 to 1500m  Main thermocline rarely breaks down & in open ocean  Deep or bottom layers Below 1500 m typically less than 4°C

26.  Water column with less dense water on top and dense water on bottom with no mixing is stable  Depends on the difference in densities between layers  If difference is small not much energy is needed to mix the water  Downwelling occurs when top layers become more dense & sinks  The sinking water displaces and mixes with deeper water (overturn)  Density & temperature profiles are straight- lined  Temperate and polar during winter

27.  Mixing layers extends greater into water column  Important to productivity  In intense downwelling, large volume of water may leave without mixing  Changes in salinity at surface  ¨ Precipitation, evaporation, freezing, and temp.  Once water sunk it does not change in salinity and temp. (water mass)  Oceanographers can follow the circulation over large distances  Because it is driven by density (determined by temp and salinity) the circulation is called thermohaline circulation

28.  Only places where surface overturn reaches the bottom is Atlantic south of Greenland & north of Antartica  The sinking water spreads though the Atlantic & other ocean basins then eventually rise to surface and flows back  Recycles about every 4000 years  Regulates climate and alterations have produced rapid climate changes (ie ice ages)  Bring dissolved oxygen to deep sea

30.  A. Waves  Caused by wind  Parts of a wave  Wave crest: moves up & forward  Trough: moves down and back  Water particles do not go anywhere!!  Move in a circle  Faster (the longer the wind the bigger the waves)  Fetch-span of open water  Larger the fetch, the bigger the wave

31.  Seas  Sharp peaks stretch over trough  Move away and get faster than speed of wind  Swells  Once waves settle  Surf  Bottom forces water to move  elongated ellipses  Wavelength get shorter  Waves “pile up” becoming higher & steeper until they fall forward

32.  Water affected by mixture of waves  Two crest adding to make a higher wave (wave reinforcement)  ¨ As high as ten stories  Trough & crest combine & cancel out the wave

33.  Influence marine organisms  Organisms are exposed & submerged on shore  Drive circulation of bays and estuaries, trigger spawning

34.  Gravitational pull of sun & moon & rotation of Earth, moon, & sun Moon’s influence  gravity strongest on side of earth closest - pulls water in ocean toward it  Opposite side furthest from moon - pull is weakest  earth’s rotation is like unbalanced tire (wooble) creates a centrifugal force - makes the oceans bulge out toward the moon & away from moon

35.  2 high tides and 2 low tides in 24 hours and 50 minutes  extra 50 min because for earth to catch up to moon  Sun ½ as strong as moon because so far away  Full & new moon (sun moon in line)  ¨ Tidal range (difference between high and low tide) is large  ¨ Spring tides  First and third quarter  ¨ Sun & moon at right angles partially cancel each other out – tidal range small  ¨ Neap tides

36.  Tides vary depending on location  and the shape and depth of the  basin  East coast of N. America & most of  Europe & Africa have semidiurnal  tides (2 highs and 2 lows)  West coast of USA & Canada mixed  semidiurnal tide- 2 high and two low  Diurnal ( 1 high and 1 low) rare on Antarctica and parts of Gulf of Mexico, Caribbean, &Pacific  Tide tables give predicted time and height of high and low tides  Determined by local geology  Weather like