Oceanography

Oceanography 71% Earth’s surface is water 61% Northern Hemisphere is water 81% Southern Hemisphere is water Average temperature 39o F Average depth 12,451 feet Average land elevation 2772 feet

Formation of Oceans Earth the Biography: Oceans Volcanic outgassing Water vapor given off Cooled and condensed Comets colliding with Earth

Significance of Oceans Maintaining Earth’s temperature -70o C to 55o C Mercury -180o to 430o C Absorbs heat from sun Currents move hot to cold Air temperature Coastlines more moderate Inland more extremes Water loses / gains heat slower than Land

Significance of Oceans Biodiversity Majority of all Earth’s Biomass Source food and oxygen Vast complicated food web Water Cycle Starting point Earth’s water cycle

Salinity Salts 3.5 % mass of oceans Varies with location Affected by Mouth river – lower Dead sea – 30% Location in water column Affected by Precipitation Sea ice / Icebergs melting Runoff from land Evaporation Formation of sea ice

Ocean Temperature Varies with amount solar radiation received Function of latitude Varies with depth Thermocline Layer of ocean 300 m to 1000 m Rapid change of temperature with depth Creates barrier to marine life

Density Density = mass per unit volume Seawater density affected by Salinity Temperature Varies with depth Pycnocline Layer ocean water 300 – 1000 meters Rapid change of density with depth

Composition Na Mg other Cl Ca S

Water Columns Photic zone Epipelagic zone Sunlight zone Depth sunlight penetrates Down to 200 meters Photosynthesis Highest amount of nutrients and energy

Water Columns Disphotic zone Mesopelagic zone Twilight zone Scarce light 200 – 1000 meters down High pressures

Water Columns Aphotic zone Midnight zone Bathypelagic zone 90% of the ocean No light – no photosynthesis Few life forms Extremely high pressures

Water Zones littoral High tide to low tide Constant motion Intertidal zone littoral High tide to low tide Constant motion Exposure to large amounts of air

Water Zones sublittoral From intertidal zone to end continental shelf Neritic sublittoral From intertidal zone to end continental shelf Oceanic plants High primary production Majority of sea life

Water Zones Begins at end of continental shelf Oceanic zone Begins at end of continental shelf Steeper dive to ocean floor Mostly no sunlight Sharks, whales, etc.