presentation oceanography

OCEAN CURRENTS

GROUP MEMBERS

Maheen RazaQurat-ul-Ain Ali

Nida Najabat

CONTENTS

•INTRODUCTION•CAUSES OF FORMATION OF OCEAN CURRENTS•TYPES OF OCEAN CURRENTS•STRENGTH OF OCEAN CURRENTS •TYPES OF DANGEROUS CURRENTS•IMPORTANCE OF OCEAN CURRENT

INTRODUCTION•Permanent or continuous directed movement of water•Vertical and horizontal movement •Vary in size and strength•Warm ocean current and Cold ocean current •California currents in Pacific, Gulf stream, Indian monsoon current in Indian ocean

CAUSES OF FORMATION OF OCEAN CURRENTS

Moon’s gravitational pull• Gravitational attraction

forms tides• Falling and rising of tides

forms currents • Known as Tidal currents• Found in bays and near

shores • Have regular pattern

Wind•Stress of wind in upper layer of water •Winds drive current near coastal area on a localized scale•Winds drive current in open ocean on a global scale

Density Difference•Depends upon temperature and salinity•Less dense heated water moves above cold water•Gives off heat, cools and sinks•Thermohaline circulation•Transport oxygen, heat and nutrients

Occasional Events

•Huge storms•Underwater earthquake Tsunamis

TYPES OF OCEAN CURRENTS

1) Surface current (Surface circulation)

•Make about 10% of all ocean water •Upper 400m of ocean •Solar heating, winds and gravity •Circular pattern (gyres)•Coriolis effect (deflection of air due to rotation of earth)

•Clockwise spirals in northern hemisphere•Anticlockwise spirals in southern hemisphere•Deep and narrow or shallow and wide •Carry heat so affect regional climates •Eddies (swirling loops of water)•Example : GULF STREAM

2) DEEP OCEAN CURRENTS•Make 90% of worlds ocean•Formed due to temperature, salinity and density difference•Global convey best (constantly moving system of deep ocean driven by temperature and salinity difference )•Submarine river (flow under surface of oceans)•Very slow and hidden from immediate detection •1000 years to complete one full circuit of globe

STRENGTH•Wind speed •Precipitation •Shape of ocean floor •Evaporation •Inflow from river and adjacent seas

TYPES OF DANGEROUS CURRENTS

1) Rip currents • Waves break over a sand bar

near shoreline • Water gets trapped between

sandbar and shore • Water releases pressure by

returning back to lake in form of rip current

• Powerful and hazardous for swimmers

2) Structural Currents•Found alongside structure like break walls •Dangerous•Washing machine effect •Swimmers moved back to lake with no path

3) Long Shore Currents

•Move parallel to or along shoreline • Exert force to move along shore

IMPORTANCE OF OCEAN CURRENT

•Absorb moisture and heat so determine weather system •Transport cold and warm water so determine climate •Maintain marine life by circulating nutrients •Shapes the features of earth •Marine power generation