Chapter 3 Chemical And Physical Features of the World Ocean Copyright, 1996 © Dale Carnegie & Associates, Inc. Mrs. Dow Marine Science Mosley High School

Sunshine State Standards Explain how the physical and chemical properties of sea water and the geology of the ocean basin shape the nature of oceanic life. SC.B understand how knowledge of energy is fundamental to all the scientific disciplines. SC.B Understand that there is conservation of mass and energy when matter is transformed.

Sunshine State Standards SC.D know how climatic patterns on Earth result from an interplay of many factors (Earth’s topography, it rotation on its axis, solar radiation, the transfer of heat energy where the atmosphere interfaces with land and oceans, and wind and ocean currents).

I.Water’s Unique Properties A. Water’s molecular structure enables life to exist on Earth. H 2 O H+ H+ 1. Each hydrogen shares an electron with the oxygen atom. O-

2. The unequal sharing of electrons forms a Covalent Bond. 3. Water is a polar molecule, meaning it has a positive end and a negative end. 4. H 2 O molecules are joined together by hydrogen bonds, a weak attraction 5. Water has a high surface tension because of hydrogen bonds.

Water molecule

Hydrogen Bonds

B. The States of Water 1. Water is the only substance that naturally occurs in all three states (solid,liquid and gas). 2. As liquid,water molecules move constantly,hydrogen bonds hold small groups of them together. 3. As the temperature rises so does the movement of the molecules. Evaporation occurs when the water molecule moves fast enough to break free of all the hydrogen bonds.

a. evaporation - process where the molecules go from liquid phase to the gaseous phase. 4. When liquid cools, the molecules not only move slower,they pack closer together and take up less space. a. As water gets colder it get more dense. b. H 2 O is most dense at 4°C, after that the ice crystals prevent the water molecules from getting closer. C. O°C is the freezing point of water.

C. Heat and Water 1. Water has a high heat capacity - its ability to resist rapid temperature changes. 2. Water has a high latent heat of melting- the amount of heat energy needed to melt a substance, that is to change it from solid to a liquid.

3. Water has a high latent heat of evaporation- the amount of heat energy to evaporate a substance, that is, to change it from a liquid to a gas. D. Water as a Solvent 1. Water is often referred to as a universal solvent. 2. Water molecules act like tiny magnets and attack the salt and pull them apart or dissociate(dissolves) each crystal

II. Composition of Seawater A. Six major components of seawater Chlorine 55.03% Sodium 30.59% Sulfate 7.68% Magnesium 3.68% Calcium 1.18% Potassium 1.11%

B. Principle of constant proportions- the proportion of ions in the seawater remains the same throughout the oceans. C. Salinity- the amount of dissolved materials in seawater.(measured in part per thousand) 1. Two important processes add salts (solids) to the oceans: a. river discharge b. Water circulating through hydrothermal vents

Processes that add salts to the oceans

D. Although the proportions remain the same, the concentrations vary due to evaporation and precipitation.(average salinity is 35% ) E. Saltiest- Red Sea / 40% Freshest- Baltic Sea / 7% F. Two important factors that affect density 1. Temperature- density increases as the temperature decreases.(until it reaches 4 C) 2. Salinity- density increases as the salinity increases.

G. Dissolved Gases in Seawater 1. The three most important gases for life in the ocean are oxygen, carbon dioxide, nitrogen. 2. All three of these are found in the earth’s atmosphere and dissolve at the sea surface. Sometimes the reverse occurs and the sea releases gases into the atmosphere. 3. Diffusion of oxygen from the ocean accounts for over 50% of atmospheric oxygen.

H. One of the most biologically important properties of seawater is that it is relatively transparent so that sunlight can penetrate fairly deep into the ocean. 1. Sunlight contains all the colors of the visible spectrum, but not all colors of light penetrate equally as well. a. The ocean is most transparent to blue light, other colors are absorbed more than blue. B. www. punaridge.org

I. Pressure- is another factor that changes dramatically with depth in the ocean. 1. Organisms on land are under 1 atmosphere ( 14.7 pounds psi) of pressure at sea level. 2. With each 10 meters (33 feet) of increased depth, another atmosphere of pressure is added.

III. Motion in the Ocean A. Surface Circulation- the most intense motion of the oceans occur at the surface in forms of surface currents and waves. 1. Both currents and waves are driven by the wind, which is driven by the sun.

2. Coriolis Effect- deflects large-scale motions like the wind and currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. 3. Wind Patterns- are driven by heat energy from the sun. A. At the equator, most of the solar energy is absorbed and the warm air rises Trade winds- adjacent wind to equator gets sucked in to replace the rising air at the equator.

4. Surface currents a. equatorial currents move parallel to the equator. b. Gyres- are huge,more or less circular systems of wind-driven surface currents. B. Waves- are disturbances (energy) that move along the surface of the water.

B. Waves- are disturbances (energy) that move along the surface of the water Crest- the highest part of a wave 2. Trough- the lowest part of a wave 3. Wavelength- distance between successive crest or troughs 4. Wave height- vertical height from the top of the crest to the trough 4

5. Period of a wave-the time it takes to go by any given point. 6. Fetch- the span of water which the wind blows. C. Tides are caused by the gravitational pull of the moon and sun and by the rotation of the earth,moon and the sun. 1. Spring tides- occur when the sun and moon are in line with each other 2. Neap tides- occur when the sun and moon are at right angles with each other

Spring Tides

Neap Tide

3. Three general types of tides a. Semidiurnal tides- have two equal high and low tides each day example: east coast of N.America, most of Europe and Africa b. Mixed tides- have successive high tides of different heights example:West coast of U.S. and Canada c. Diurnal tides- occur when there is only one high and one low tide each day example:Gulf of Mexico, Antarctica, Panama City Beach