Oceanography Sarah Hall

Marine Biology vs. Oceanography Marine Biology is the study of life in the ocean. Oceanography is the study of the physical characteristics of the ocean

Physical Characteristics of Water Color Temperature Turbidity- cloudiness Salinity- saltiness Pressure Currents Density

The Water Planet Our Earth is made up of 71% water. Our Earth is made up of 71% water. Most of that water is marine (salt). Most of that water is marine (salt). Less than 10% of the Earth’s water is freshwater. Less than 10% of the Earth’s water is freshwater. Of that 10% less than 3% is drinkable! What is the other 7%? Of that 10% less than 3% is drinkable! What is the other 7%?

Where are they Found?

Hydrogen bonding Hydrogen bonds: Unique attractive forces between polar molecules, including water. They are the result of attraction between the H of one water molecule and the Oxygen of another water molecule.

Surface Tension Surface Tension: Allows water molecules to form a tight surface layer.

Salinity The measure of dissolved solids in sea water. Most common is sodium chloride Average is 3.5% Changes with latitude – Higher latitude it decreases due to little evaporation – Lower latitudes the fresh water is being evaporated

Salinity Average Salinity: 35% in oceans, expressed in parts per thousand (ppt). Other trace elements are expressed in parts per million (ppm). Salinity at the poles: High due to freezing, removing water from the sea. Salinity at the equator: Low due to precipitation.

Temperature Temperature decreases rapidly with depth as the sun does not reach very deep. – Surface zone – warm light penetrates mixed layer - wind and waves mix it up – Thermocline – zone of rapid temperature change – Deep - cold zone

Thermocline

Bathymetry Study of the ocean floor (topography) Continental shelf – underwater part of the continent Continental slope – seafloor depth increases rapidly Submarine canyons – turbidity current cuts into slope Abyssal plains – plains of the ocean floor Seamounts and guyots - cone shaped mountain peaks Trenches – oceanic crust goes under contintal crust Mid-ocean ridge – rift valley, undersea mountain ranges

Ocean currents Surface currents – Broad path of flowing water in a specific direction – Driving force is wind Trade winds – Near the equator – blow water toward the west Westerly winds – Drive the polar portion of the ocean currents

More on surface currents Warm currents – flow away from the equator – Gulf stream is an example, helps moderate climate in the eastern portion of the US. Cold currents – flow from the poles – Labrador current is an example, sneaks into the gulf of Maine to cool down New England.

Density Currents (Deep currents) Occurs when water becomes more dense due to temperature changes or salinity changes Much evaporation leaves the water with a higher salinity creating a denser water which sinks. ( warm, dry climates ) Cooling contracts water making it denser and it sinks as it arrives in the poles.

Upwelling Vertical current in the ocean. When cold deep ocean water comes to the surface. Separating wind belts, Bathymetry, (topography), and surface water away from the coast. Contains large amounts of nutrients which starts a large food chain reaction.

The Oceans and Global Warming An imbalance of heat received versus heat leaving the earth can lead to either warming or cooling. The majority of heat transferred from earth to the atmosphere is transferred by evaporation of water. Carbon Dioxide CO 2, Methane CH 4, and Chlorofluorocarbons are considered greenhouse gases.

Formation of Waves Waves: A common wave is generated by wind. Tsunamis: shallow water waves generated by shifting of the ocean floor.

Waves Up and down movement of the water surface When the wind blows it pushes on the earths surface causing the water to lift. Bigger wave – greater speed, length of time, and distance Wave length – distance between two consecutive crests Wave height – distance from crest to trough

Wave terms

Tides Daily rise and fall of the ocean. Tidal range – distance between high and low tide Semidiurnal – two times a day (6 hr 20 min) Ocean bulges out facing the moon due to gravity – Spring tide – sun and moon align – Neap tide – sun and moon are at right angles

Tides Neap tide: rising tide Ebb tide: a falling tide Semidiurnal tide: a tidal pattern of two equal high and low tides per day.