THE OCEANSTHE OCEANS

ENDURING UNDERSTANDINGSENDURING UNDERSTANDINGS

• Earth is an ocean planet.Earth is an ocean planet.

71% of Earth’s surface is covered by water.71% of Earth’s surface is covered by water.

• The global ocean is the major contributor to the The global ocean is the major contributor to the water cycle.water cycle.

• The oceans store most of the thermal energy The oceans store most of the thermal energy received from the sun. received from the sun.

THE GLOBAL OCEANTHE GLOBAL OCEAN

• The global ocean is divided into 5 major The global ocean is divided into 5 major

regions: the Pacific, Atlantic, Indian, regions: the Pacific, Atlantic, Indian,

Southern (or Antarctic) and Arctic oceans.Southern (or Antarctic) and Arctic oceans.

Antarctic Ocean

HOW DID THE OCEANS FORM?HOW DID THE OCEANS FORM?

• Between 4.5 and 4 billion years ago, as the Earth Between 4.5 and 4 billion years ago, as the Earth cooled, water vapor began to condense and fall as cooled, water vapor began to condense and fall as rain. rain.

• The water vapor had accumulated from volcanic The water vapor had accumulated from volcanic gases and ice from comets.gases and ice from comets.

SALINITYSALINITY

• Salinity is a measure of dissolved salts and solids Salinity is a measure of dissolved salts and solids in a given amount of liquid. in a given amount of liquid.

• Ocean salinity comes from minerals & rocks on Ocean salinity comes from minerals & rocks on land eroded and carried by streams to oceans. land eroded and carried by streams to oceans.

• Higher salinity occurs where evaporation is higher Higher salinity occurs where evaporation is higher than input, freezing removes fresh water, areas of than input, freezing removes fresh water, areas of low river runoff, or mixing by currents is low. low river runoff, or mixing by currents is low.

• The composition of the ocean salinity is 55% Cl, The composition of the ocean salinity is 55% Cl, 30.6% Na, 7.7% Mg, 3.7% S, 1.2% Ca, 1.1% K and 30.6% Na, 7.7% Mg, 3.7% S, 1.2% Ca, 1.1% K and other solids. Most ocean salt is NaCl.other solids. Most ocean salt is NaCl.

THE THERMOCLINETHE THERMOCLINE• The thermocline is a layer of water extending from the The thermocline is a layer of water extending from the

surface zone to the deep zone where water temperature surface zone to the deep zone where water temperature drops rapidly.drops rapidly.

• The temperature of the surface zone depends on the amount The temperature of the surface zone depends on the amount of thermal heating. The temperature of the deep zone is a of thermal heating. The temperature of the deep zone is a relatively constant 2relatively constant 2ooC throughout the global ocean.C throughout the global ocean.

THE WATER CYCLETHE WATER CYCLE

• The water cycle is the movement of water between The water cycle is the movement of water between the ocean and atmosphere by evaporation, the ocean and atmosphere by evaporation, condensation and precipitation. condensation and precipitation.

• The global ocean is the major contributor to the The global ocean is the major contributor to the water cycle.water cycle.

A GLOBAL THERMOSTATA GLOBAL THERMOSTAT

• Oceans store most of the Oceans store most of the thermal energy received from thermal energy received from the sun. the sun.

• The angle of the sun’s rays The angle of the sun’s rays determines the amount of determines the amount of solar radiation absorbed. solar radiation absorbed. Rays strike high latitudes at Rays strike high latitudes at low angles but strike the low angles but strike the tropics at nearly 90tropics at nearly 90oo..

• Oceans store thermal energy Oceans store thermal energy because water has a high because water has a high heat capacity. heat capacity.

THE OCEAN FLOORTHE OCEAN FLOOR• The continental margin is divided by depth and slope into the continental The continental margin is divided by depth and slope into the continental

shelf, continental slope, continental rise, abyssal plain, mid-ocean ridges and shelf, continental slope, continental rise, abyssal plain, mid-ocean ridges and rift valleys, with features such as seamounts and ocean trenches. rift valleys, with features such as seamounts and ocean trenches.

• Scientists study the ocean surface and floor using sonar and satellites. Scientists study the ocean surface and floor using sonar and satellites.

LIFE IN THE OCEANLIFE IN THE OCEAN• Plankton float in the water column, nekton swim Plankton float in the water column, nekton swim

under their own power and benthos live in or on the under their own power and benthos live in or on the ocean floor. ocean floor.

OCEANIC ZONE NERITIC ZONE PHOTIC ZONE

SUPRALITTORAL ZONE (Splash Zone)

200 meters

4000 meters 6000 meters

SUBLITTORAL ZONE (Subtidal Zone) LITTORAL

ZONE (Intertidal Zone)

C O N T I N E N T A L S L O P E

C O N T I N E N T A L S H E L F

BATHYAL ZONE

APHOTIC ZONE

PELAGIC REALM

BENTHIC REALM

ABYSSAL ZONE

C O N T I N E N T A L R I S E

HADAL ZONE

OCEAN ZONESOCEAN ZONES

The benthic environment The benthic environment is the ecological zone is the ecological zone where benthos live, where benthos live, divided by depth into the divided by depth into the supralittoral, littoral, supralittoral, littoral, sublittoral, bathyal, sublittoral, bathyal, abyssal and hadal zones. abyssal and hadal zones.

The pelagic The pelagic environment is the environment is the water column divided water column divided into the neritic zone, the into the neritic zone, the water above the water above the continental margin, & continental margin, & the oceanic zone, the the oceanic zone, the water of the open water of the open ocean. Most ocean life ocean. Most ocean life lives in the neritic zone.lives in the neritic zone.

SHELF BREAK

SURFACE CURRENTSSURFACE CURRENTS• Surface currents are streams of water near the surface Surface currents are streams of water near the surface

of the ocean controlled by global winds, the Coriolis of the ocean controlled by global winds, the Coriolis Effect and continental deflections. Effect and continental deflections.

• Currents Currents distribute distribute thermal energy thermal energy stored by the stored by the ocean, keeping ocean, keeping Earth’s climate Earth’s climate mild. mild.

• Surface currents Surface currents affect climate by affect climate by distributing distributing thermal energy. thermal energy.

EARTH’S SURFACE CURRENTSEARTH’S SURFACE CURRENTS• Currents flowing from poles toward the equator carry Currents flowing from poles toward the equator carry

cold water. Currents flowing from the equator toward cold water. Currents flowing from the equator toward poles carry warm water.poles carry warm water.

THE CORIOLIS EFFECTTHE CORIOLIS EFFECT

• Earth’s rotation Earth’s rotation causes wind and causes wind and surface currents to surface currents to curve to the right in curve to the right in the northern the northern hemisphere and to hemisphere and to the left in the the left in the southern southern hemisphere. hemisphere.

DEEP WATER CURRENTSDEEP WATER CURRENTS

• Deep currents are driven by density differences Deep currents are driven by density differences determined by temperature and salinity, & flow determined by temperature and salinity, & flow from the poles toward the equator.from the poles toward the equator.

CIRCULATION CIRCULATION

OF DEEP & OF DEEP &

SURFACE SURFACE

CURRENTSCURRENTS

EFFECTS OF CURRENTSEFFECTS OF CURRENTS

• Upwelling is the rising of deep bottom water to the Upwelling is the rising of deep bottom water to the surface, carrying nutrients to the surface and surface, carrying nutrients to the surface and replacing warm surface waters. replacing warm surface waters.

• El Nino is the interruption of upwelling along the El Nino is the interruption of upwelling along the western coast of SA, and the spread of warm water western coast of SA, and the spread of warm water into the Pacific. Temperature change and lack of into the Pacific. Temperature change and lack of nutrients greatly affect wildlife.nutrients greatly affect wildlife.

SURFACE WAVESSURFACE WAVES

The size of waves is determined by:The size of waves is determined by:

• The strength of the windThe strength of the wind

• The length of time the wind blowsThe length of time the wind blows

• FetchFetch

PARTS OF A WAVEPARTS OF A WAVE

WAVE PERIODWAVE PERIOD

WAVE FREQUENCY & WAVE SPEEDWAVE FREQUENCY & WAVE SPEED

• Wave frequency is the number of waves that pass a Wave frequency is the number of waves that pass a stationary point in a given amount of time.stationary point in a given amount of time.

DEEP vs SHALLOW-WATER WAVESDEEP vs SHALLOW-WATER WAVES

• Deep-water waves become shallow-water waves Deep-water waves become shallow-water waves when wave base touches the bottomwhen wave base touches the bottom

MOON PHASESMOON PHASES

NEW MOONNEW MOON

CRESCENTCRESCENT

11STST QUARTER QUARTER

GIBBOUSGIBBOUS

FULL MOONFULL MOON

GIBBOUSGIBBOUS

33RDRD QUARTER QUARTER

CRESCENTCRESCENT