Water, Waves, and Tides

1. Water, Waves, and Tides The Nature of Water : Physical properties of water: 1. Most marine organisms are 70-80% water by mass. 2.Water molecules are polar due to uneven attraction of electrons to the oxygen atom. 3. Hydrogen bonds result between the hydrogen of one water molecule and the oxygen of another water molecule. Increases heat capacity. 4. Frozen water is less dense than liquid water.

2. Surface tension- property characterized by clinging together of molecules at the surface of water by cohesive forces. Cohesion- property of water whereby molecules tend to stick to one another. Accounts for surface tension.

3. Adhesion- property of a liquid in which it is attracted to the surface of objects that carry an electrical charge. Accounts for capillary action. Chemical Properties of Water: Ph scale- indicator of the number of hydrogen ions in a solution. 0 < 7 acidic 7 or > base

4. Salt Water: 1. Average salinity is 35 parts per thousand 2. NaCL is the most common salt present. Other elements present, but in concentration less than one part per million are trace elements. 3. Trace elements are present in concentrations less than 1 part per million. However they are still important for living organisms. 4. Salinity of surface seawater varies with latitude and topographical features of an area. Ex. Salinity of seawater at the poles is high due to freezing.

5. Cycling of Sea Salts: The most important process for the removal of salt from the oceans is by the sticking of ions onto particles known as adsorption. Gases in Seawater Amount of oxygen and nitrogen in air is about the same in seawater. Carbon dioxide is however higher in seawater than air.

6. Ocean Heating and Cooling: 1. Only 47% of incoming solar radiation is absorbed by the earth’s surface 2. Majority of heat that is transferred from the earth to the atmosphere is transferred by evaporation 3. Density of air increases with decreasing moisture.

7. Ocean Layers and Vertical Mixing: • Density equals mass of a substance divided by its volume • 2. The two main factors controlling the density of water are • salinity and temperature. Salinity is more important in • determining the density of surface waters. 3. Maximum density of water occurs at 4° C. Thermocline- zone of rapid temperature change. Halocline- zone of rapid change in salinity with depth.

8. Vertical Mixing: Isopycnal- same density from top to bottom in a water column. Downwelling- areas where surface water is sinking. Upwelling- areas where bottom rises to the surface.

9. Winds and Currents: Coriolis Effect- in the Northern Hemisphere air is deflected to the right of air movement. 1. A common wave generating force in the ocean is wind. By generating waves it also drives surface currents. 2. Areas between wind convection cells are characterized by having stable and consistent winds.

10. Waves: Restoring force- force that causes the water to return to the undisturbed level. Capillary wave- wave for which the restoring force is the surface tension of the water. They are small waves. Period- time required for one wavelength to pass a fixed point.

11. Fetch- distance over the water that the wind blows. Deepwater waves- waves that occur in water that is deeper than half a waves wavelength. Plunging waves- form when the beach slope is steep. Tsunami- large shallow water sea wave that results from a seismic disturbance. Increases in amplitude as it approaches the shore.

12. Tides: Tides- are the result of gravitational pull on the oceans by the moon and the sun. Moon plays a greater role in producing tides. Spring tides- the greatest change between high and low tide marks. Neap tide- smallest change between high and low tide . Diurnal tide- one high and one low tide each day. Semidiurnal tide- two high and two low tides. Flood tide- rising tide. Ebb tide- falling tide. Slack water- period during the change of ebb tide from high to low or visa versa.