Presentation Transcript

1. Salt Water
2. How Ocean Water Differs from Fresh Water Ocean water’s salinity = 200X greater than fresh water Average salinity of oceans is 35 ppt (parts per thousand) Oceans at equator (because of evaporation) and poles (the creation of ice) have the highest salinity removing water increases salinity Ocean locations near rivers have low salinity, due to addition of fresh water from the World Ocean Atlas 2001
3. Oceans 70% of the Earth’s surface is covered by oceans Oceans are the largest ecosystem on Earth 97% of the water on Earth in oceans (too salty to drink) All oceans are connected Light only goes down 100 meters, so most of the oceans are pitch black Oceans undergo constant change
4. Composition of Salt Water Salt water is composed of minerals dissolved during run-offs occurring over millions of years Volcanic eruptions also release minerals from inside Earth
5. The Origin of Ocean Water Oceans have filled over hundreds of millions of years. Scientists believe the oceans are more than 3 billion years old. Water may have originally been released from volcanic eruptions, or arrived on Earth via icy comets. (c) McGraw Hill Ryerson 2007
6. Ocean Basins The surface of the ocean floor is as varied as the land. The five major oceans, from largest to smallest, are the Pacific the Atlantic the Indian the Southern the Arctic The low points in the oceans are called basins. Oceans are vital to life, as they control temperature, create weather patterns and provide water for water cycles. (c) McGraw Hill Ryerson 2007
7. Ocean Basins The largest changes to the ocean basin occur through the movement of tectonic plates, although there is also erosion via storms, earthquakes and icebergs. Mid-ocean ridges occur where new rock is forced up, and ocean floor spreads outward. The Mid-Atlantic Ridge is the largest example on Earth The Juan de Fuca plate lies 200 km off Vancouver Island A trench forms when the dense oceanic plates run into, and slide under, the continental plates. (c) McGraw Hill Ryerson 2007
8. Ocean Basins (continued) Abyssal plains are the pieces of oceanic crust between a spreading mid-ocean ridge and the trench it disappears into. These make up 30% of the Atlantic sea floor, and 65% of the Pacific seafloor. Abyssal plains can be covered in 1 km of sediments Seamounts are old volcanic mountains found on abyssal plains. The Hawaiian Islands are an example. See page 407 (c) McGraw Hill Ryerson 2007
9. Continental Margins Continental margins are part of continental plates. Continental margins are made up of a continental shelf (averaging 80 km wide) and a continental slope down to the oceanic plate. Continental shelves were above water during the last ice age. (c) McGraw Hill Ryerson 2007
10. Ocean Currents There are more than 20 major currents which move large amounts of water predictably around the oceans. Currents move large quantities of water, minerals, solar energy, oxygen and carbon dioxide, plankton and fish. Currents are caused and driven by water density and salt content, the wind, the spin of Earth, coastlines and the moon. Largest current is the Antarctic Circumpolar Current in the Southern Ocean, at 24 000 km long Ocean currents are either Surface currents (0 - 200 m) Deep water currents (200 m and deeper) (c) McGraw Hill Ryerson 2007
11. Ocean Waves and Their Effect on Shaping Land Most waves are created by wind. In open ocean, waves are called swells. Swells “break” in shallow water, show characteristic curl. The largest waves are tsunamis, caused by undersea earthquakes, landslides or volcanic eruptions. Waves erode coastal areas based on the force of the waves, and the composition of the shoreline. (c) McGraw Hill Ryerson 2007
12. Tides Tides are caused by gravities of Earth and the Moon. High tides occur where the Moon is closest to Earth (and opposite side) Low tides occur at 90º to the high tides. Tidal rangeis the difference between high and low tide The Sun’s gravity, when lined up properly, can produce extreme tides. These are called spring tides When the Sun, Moon and Earth are not lined up, the tides are called neap tides. (c) McGraw Hill Ryerson 2007
13. Oceans and Climate Water has a high heat capacity Water heats up and cools down slowly, and can absorb large amounts of thermal energy.  Oceans can store and transport huge amounts of energy Oceans influence weather through the water cycle Weather tracked over many years = climate Climates vary greatly around the world Climate measures temperature + precipitation > 30 years (c) McGraw Hill Ryerson 2007
14. How Oceans Affect Weather Through convection, heat energy transfers from the ocean’s surface to the air, and this warm air rises The warm “bubble” of air is called a thermal The thermal rises until it loses its heat, and then drops back down again. This process of heat transfer is called convection. El Niño is the warming ocean effect that occurs some years in December off the Pacific coast of Ecuador. El Niño can change the weather around the world, including warmer and wetter in BC, and droughts in Africa and Australia. Changing ocean temperatures also cause sea life to change behaviours. La Niña is a cooling of similar waters, and produces almost the opposite effects of El Niño. (c) McGraw Hill Ryerson 2007
15. The Moderating Effect of Oceans on Climate Oceans can make cold, northern locations warmer Locations like BC, Norway and England benefit Because of water’s high heat capacity, heat energy can be carried from south to north by currents like the Gulf Stream (in England and Norway) or the Pacific Drift (in BC). As the warm water evaporates, it carries energy over the mainland of the province. Mountains block the warmth from reaching into the interior. Edmonton and Manchester, England are the same latitude Edmonton, Alberta January average temperature = 7 C Manchester, England January average temperature = +6 C