Ocean Current

-

Primary forces that initiate the movement of water

  • Heating by solar energy – Expand water, so near the equator the ocean water is about 8 cm higher in level than in the middle latitudes.
  • Wind – Water to Move.
  • Gravity -  Pull the water down the pile and create gradient variation.
  • Coriolis force - water to move to the right in the northern hemisphere and to the left in the southern hemisphere.
Secondary forces that influence the currents to flow
  • Large accumulations of water and the flow around them are called Gyres.
  • Differences in water density affect vertical mobility of ocean currents.
    • High salinity > Low Salinity.
    • Cold water > Warm water.
  • Denser water - sink, while relatively lighter water tends to rise.
  • Cold-water currents occur when the cold water at the poles sinks and slowly moves towards the equator.
  • Warm-water currents travel out from the equator along the surface, flowing towards the poles to replace the sinking cold water
Types of Ocean Currents
Based on Depth
  • Surface currents – 10 %, upper 400 m of the Ocean.
  • Deep water currents – 90 %
Based on Temperature
  • Cold currents bring cold water into warm water areas.
  • Warm currents bring warm water into cold water areas.
Major Ocean Currents
  • Oceanic circulation pattern roughly corresponds to the earth’s atmospheric circulation pattern.
  • Middle latitude – anticyclonic. & Higher latitude – Cyclonic.
  • Monsoon winds influence the current movements.
  • Cold waters of the Arctic and Antarctic circles move towards warmer water in tropical and equatorial regions.
  • Warm waters of the lower latitudes move poleward.
Effects of Ocean Currents
  • West coasts of the continents in tropical and subtropical latitudes (except close to the equator) are bordered by cool waters - fog, but generally the areas are arid.
  • West coasts of the continents in the middle and higher latitudes are bordered by warm waters which cause a distinct marine climate - cool summers and relatively mild winters.
  • Warm currents flow parallel to the east coasts of the continents in tropical and subtropical latitudes - warm and rainy climates.
  • Areas lie in the western margins of the subtropical anti-cyclones.
  • Mixing Zone - mixing of warm and cold currents help to replenish the oxygen and favour the growth of planktons, the primary food for fish population.

Comments

Post a Comment

Popular posts from this blog

Indian Painting - Pre History

-
Image
    History and Evolution of Painting in India - An Overview India has a long tradition of artistic excellence and painting is one of the major mediums that has been used to express it. There is several evidence suggesting that painting flourished in India since ancient times. Archaeologists have found wall paintings in parts of India, which suggest that even the early historic man in India was engaged in activities of art and leisure The history of painting can be traced through the ancient and medieval period where the books were illustrated with paintings Then came the miniature style that dominated the Mughal and Rajput courts. With the coming of the Europeans, the art of painting and engraving took a western turn. Modern painters experimented with styles, colours and designs. Many Indian painters have gained worldwide recognition and are winning prizes and accolades for their vision. Principles of Painting The history of paintings can be known from primitive rock paintings of Bhim
Read more

Classification of Indian Paintings

-
Image
    Classification of Indian Paintings Indian Paintings have been broadly classified into two. Mural Paintings Miniature Paintings Mural Paintings The work on the walls or a solid structure are referred to as Murals. These have existed in India since ancient times and can be dated between 10th century BC and 10th century AD. The evidence of such paintings can be found at several locations in India. The beauty and the exquisiteness of mural paintings can be seen in places like Ajanta, Armamalai Cave, Ravan Chhaya Rock Shelter, Bagh Caves, Sittanavasal Caves and Kailash Temple in Ellora. Most of the mural paintings are either in natural caves or in rock cut chambers. The paintings follow a theme, the most common being Hindu, Buddhist and Jain. Mural paintings were also made to adorn any mundane premise. For e.g. Ancient theatre room in Jogimara Caves. Ajanta Cave Paintings One of the oldest surviving murals of Indian sub-continent, Ajanta caves were carved between 2nd century BC to 5th c
Read more

Solar system

-
Image
Galaxy Gravitational bound system of star, stellar remnants, interstellar gas, dust, and dark matter. Ex: Milky way. A galaxy is a huge system of billions of stars. Our solar system is a part of the milky way galaxy. Our Milky way galaxy was named “Akash ganga”. There are millions of galaxies that make the Universe. Distance galaxy: GN-z11 (March 2016) Hubble classification Eliptical (E) Spiral (S): Andromeda & Sombrero (unbarred) Lenticular Celestial bodies: Sun, Moon. Two types: Emit light (Star), Don’t Emit Light (Planets) North Star – Pole Star – Indicates north Direction Constellations (Group of star) – 88 Official Ursa Major – Big Dipper Tail – Alioth – Brightest in Ursa Major Saptarishi Mandal Polaris – Brightest in Ursa Minor The Sun Made up of extremely hot gases. The sun is about 150 million km away from the earth. 30 times greater than Earth. Black hole – It absorb light but does not emit due to high gravitational force. Corona – Outer surface of the sun (About 6000 k) S
Read more