Oceans The Last Frontier

Ocean Facts About 71% of Earth’s surface is covered by water Average depth of the Pacific Ocean = 4,638 m Average depth of the Atlantic Ocean = 3,872 m Average temperature = 3.9°C (39.0°F) Age of oceans = 4 billion years

Salinity in Oceans Salinity Average salinity in oceans = 35 ‰ Total amount of dissolved solids expressed in grams in 1 kg of water Average salinity in oceans = 35 ‰ 35 parts per thousand (ppt) 35 g/kg Salinity variations Due to differences in local rates of evaporation and precipitation (water budget)

Constituents of Sea Water Most abundant seawater elements are sodium (Na+) + chloride (Cl-) Major constituents: SO42-, Mg2+, Ca2+, K+, and HCO3- Minor and trace elements also present

Salts in the Ocean Why is the ocean salty? Salts come from: River discharge Volcanic eruptions Why is the ocean not getting saltier? Salts going in = salts going out

Salts Going Out Sea Sra Sea Spray Evaporites Biological Adsorption Fecal pellets Shell formation Adsorption Mid-ocean ridge magma

Factors Affecting Salinity Precipitation Evaporation River runoff Freezing

Principle of Constant Proportions The amount of salt varies, but the relative proportions of ions are constant Because of this principle, it is necessary to test for 1 salt ion (usually Cl) to determine total amount of salt present

Determining Salinity 1. Calculating Salinity Salinity=1.8065 x chlorinity (‰) 2. Salinometers Salinity determined by the electrical conductivity produced by dissolved salts

Oceans II Surface Currents

Heat Variations Latitude Depends on angle sunlight hits surface Sunlight at polar latitudes covers wider area; therefore, less heat At equator, sunlight covers less area; more heat

Heat Transfer Heat is transferred from equator to poles Air Circulation Ocean currents

Origin of Currents Ocean surface currents are wind driven Air movement due to less dense air rising and more dense air sinking Horizontal air flow along Earth’s surface is wind Air circulating in this manner is convection currents

Wind Movement Non-rotating Earth Simple wind pattern Warm air rises at equator, flows toward poles Air cools at poles, sinks, and flows toward equator Winds named by direction from which they blow North-blowing winds = southerly winds South-blowing winds = northerly winds

Wind Movement Rotating Earth At equator, warm air rises Zone of low pressure Clouds and precipitation Reaches troposphere and moves poleward As it spreads, it cools 30° N&S, cool air sinks Area of high pressure Dry conditions Location of world deserts 60° N&S, air masses meet Form Polar Front Air masses rise, diverge and sink @ 90° and 30° N&S

Wind Movement At equator, warm air rises, condenses and precipitates At 30° and 90°, cool air sinks Air that sinks does not flow back in a straight north-south path – it curves (Coriolis Effect)

Rotation on a Globe Buffalo and Quito located on same line of longitude (79ºW) Both cities circles the globe in one day (360º/24 hours = 15º/1 hour) Quito has larger circumference; thus, travels farther Quito needs to travel faster than Buffalo

Apparent Deflection Hypothetical war game If a cannonball is shot north from Quito It will travel a straight path But, because Earth is rotating east to west The cannonball appears to veer to the right in Northern Hemisphere This is the Coriolis Effect

Wind Movement Coriolis Effect Deflected winds due to movement over spinning object Produce wind bands In Northern Hemisphere: Winds are deflected to the right Travel clockwise around high P In Southern Hemisphere: Winds are deflected to the left Travel counter-clockwise around high P Assume water-covered Earth

Surface Current Circulation