an Currents and Waves [ Oceanic Waves | Waves are oscillatory motion of the ocean water ‘caused by the pushing action of the wind. Particles of water move up and down an id pass Of their ‘movement to the neighboring particles. The upper part of the wave is called crest while the lower partis known as Trough. Every wave has its own length, height, intensity and interval, The distance between two consecutive crest and trough is called Wave length. While the maximum distance travelled by crest or trough from the central point is called its amplitude. The Time taken by two consecutive waves to flow between the fixed points is called waye-period. This can be controlled by wave-velocity as it is the ratio of wave length and wave period. ‘The ocean current is generally caused due to action of wind on the ocean surface. Amplitude of the waves is affected by wind flow, the time period of its flow and the effect of ocean surface. Due to deep ocean, high wave amplitude are generated which has generally high intensity. When these waves reaches costal area then its amplitude decreases due to its movement above the disturbed water. The intensity of wave gets increased tremendously during straight end of the coast. But soon after it clash, it converted into the ocean water which is called Surf, Breaker or Swarf. The point at which the crest of the waves breaks and it changes into Swarf, from that distance to the coastal line, if we draw a parallel line then it will be known as Plung line. The wave towards coast is called Up-Wash and the wave moving towards Ocean is called Back-Wash. The coastal erosion is done by the Swarf only. After Swarf stage when wave get calm and move along with normal ocean water then its movement is called Littoral or longshore current. The ocean current also causes due to avalanche and Landslides. The ocean current which are generated due to earthquake in the ocean is called Tsunami and it is very destructive in nature Ocean Currents ‘The general movement of a mass of Oceanic water in a definite direction is called ocean current Ocean currents are classified into various types on the basis of the direction of flow, speed and shape. Geography: A Comprehensive Study [93artace 1. Delft, When the water of the « moves abcad being propelied by the called There ts po definite ve limit of a drift. The best examples of drift are The mo gyte surround the south, Gulf Atlantic Drift in the north and canary in the cast is called North and South Atlantic Drift When ocean water moves in a fixed direction within a fixed limit (of area) with very high velocity, itis called ¢ The velocity f a current 5 than that of drift When a large volume of ocean water moves with y ina fixed direction like the rivers flowing on the land surface, it called a Gulf Stream is an € ple of an oceanic stream Ocean currents can be divided into two types. warm currents and cold currents. The current flowing from the equator to the poles are warm and those flowing from pol to the equator are cold. Due to Coriolis force, the Ocean c m Hemispher Southern Hemisphe eption of this n i flow of ocean water is found in the where the direction of current flow the chan; nges with in the direction of monsoon wind flow The rotation of th results in the arth on its axis form west to ea senesis of deflective or € which deflects the direction of ocean currents. Temperature, salinity, adient and melting of i ‘Atmel density, pressuDelf When the water of the ocean surface moves ahead being propelled by the wind, itis called ditt There 1s no definite velocity or Himit of a drift. The best examples of drift are forth and South Adantic Drifts, fixed When ocean water moves with very high velocity, itis called current, The velocity clireetion within a fixed limit (ofarea of a current is more than that of drift When a large volume of ocean water moves with a great velocity ina fixed direction, like the rivers flowing on the land surface, it is called a If Stream is an example of an oceanic stream, Ocean currents can be divided into two types— warm currents and cold currents, The currents flowing from the equator to the poles are warm and those flowing from poles to the equator are cold. Due to Coriolis force, the Ocean currents in the Northern Hemisphere deflect towards their right and those in the Southern Hemisphere, towards their left. The only exception of this rule of the flow of ocean water is found in the Indian Ocean, where the direction of current flow changes with the change in the direction of monsoon wind flow. The rotation of the earth on its axis form west to east results in the genesis of deflective force or Coriolis Force which deflects the general direction of ocean currents. Oceanic factors: Temperature, salinity, density, pressure gradient and melting of i The motionless sea of subtropical North gyre surrounded by north equatorial eu the south, Gulf Stream in the west Atlantic Drift in the north and canary in the east is called The} is dirived from portuguese meaning thereby sea weed said gyre is studded with such sea wee The continuous flow of ocean curre natural effort to bring a horizontal heat b Ocean currents while flowing along the modify the local weather condition number of ways. Warm currents rai temperature of the coastal areas where: currents lower it. ‘Warm currents bring rains to the coastal because they supply moisture to the \ North Atlantic Drift brings rainfall «g General Direction of OcearWestern European parts and gives rise to a navigating vessel a ristic climate in which it rain Titanic ship w throughout the year. Unlike warm current brow cold currents do not give rise to moisture laden Current winds and hence there is no rainfall on th Ocean currents a coastal areas. These currents give rise to nutrients, Ox conditions which are the cause of desertification in the affected coastal ar Kalahari Desert is the result of cold Bangu current, whereas the Patagonia Desert is the result of the cold Falkland current 3. Cold polar currents bring with them large Ice- bergs which are a source of fresh water. But, these Ice-bergs are very dangerous for the a Kuril Current Pacific Ocea' West Wind Geography: A Comprehensive Study | 95)Newfoundland where world famous fishing. banks like Grand Bank and George's Bank have developed. The distribution of the anchovies fishes on the Peruvian coast too is related with the cold Peru or Humboldt current because it brings planktons for these fishes. Sometimes, 8 few ocean currents destroy planktons, For example, EL Nino current destroys planktons os of the Peruvian coasts and causes diseases resulting into mass deaths of gy! ish The occurrence of fogs duc to Ne convergence of warm and cold curren * Dos serious threats to navigation On which are followed by the navigating N currents act as major o ean y Oe, ships, ‘Geography: A Comprehensive Ss. Atlan’ aS I — ) eee ; [=> Cold Current — CurrentRc) Some ee ee es Wann currents keep the ports in the polar region jce-ttve throughout the year and hence making, them operational throughout the year: For e.g, mnost of the north-European ports remain ice- branches, Norway is most benefited by this drift, Murmansk port of Russia remains operational throughout the year due to the North Atlantic drift despite being in polar region. n Currents Rennell current Current Natare North Equatorial Current Hot or Warm | + — South Equatorial Current Warm + Kuroshio Current Warm * East Australian current Warm + North Pacific current Warm * Humbolt or Peruvian current Cold «Alaskan current Warm * Kuril or Oya shio current Cold | © Counter Equatorial current Warm * California current Cold «EL Nino current Warm * Antarctica current Cold © ‘Tyushima current Warm * Okhotsk current Cold | » North Equatorial current Hot or Warm | + Antilles current Warm + South Equatorial current Warm * Brazilian current Warm “+ Florida current Warm * Labrador current Cold ~~ Gulf stream Warm Canary current Cold Norwegian current Warm » Benguela current Cold Irminger current Warm * Antarctica Drift Cold ‘Counter Equatorial current Warm » Falkland current Cold Currents of the Indian Ocean (Winter) Geography: A Comprehensive Study [52stween 20° Sarg Sea situated between 2! ‘Ocean currents play an important role in 10, Sargasso aa ae... determining the monsoon of the Indian and 35' 7 subsontinent es warmest part d Th Jous potentialities of is the most saline and warmest p ere are tremendous potentia Atlantic Ocean producing power from the ocean currents. currents, ie. it does not have any coast Currents of the Indian Ocean (Summer) Indian Ocean Currents Nature Current Nature South Equatorial Current Warm & stable _ | « N-E Monsoon Current Cold & unstabli Mozambique Current Warm & stable | * Somali Current Cold & unstabl Agulhas Current Warm & Stable | + Western Australian Current Cold & Stable S-W Monsoon Current Warm & unstable South Indian Ocean Current Cold