how does shape of the coastline affect the movement of ocean current
Answers
The main effect of temperature differences on the earth occurs in a north-south direction i.e. from equator to poles. Warm equatorial waters therefore move slowly along the surface towards the poles while heavier cold waters of the polar areas creep slowly towards the Equator along the bottom of the sea. Thus, the difference in the temperature of the ocean waters causes ocean currents. They are convectional currents giving rise to a transfer of heat energy in the ocean waters from the areas of excess to the areas of deficit heat energy.
The factors relating to the earth’s nature and its rotation include the gravitational force and deflective force by earth’s rotation also known as Coriolis force.
Oceanic factors include the pressure gradient, temperature variations and salinity differences. Ex-oceanic factors are atmospheric pressure and winds, evaporation and precipitation.
Tides caused by the gravitational pull of the Moon and the Sun also play role in the forming of oceanic currents.
The factors that can modify the currents are direction and shape of coastlines, bottom reliefs of the ocean basins, seasonal variations and rotation of the earth.
Ocean circulation is driven by winds and by differences in water density. Along with the winds, ocean currents distribute the tropical heat worldwide, thus they play a very important role in maintaining Earth’s heat balance.
Please note that water at the poles travels in slow creeps below the surface water towards equator, which is called Ocean Creep. Ocean Creep is not a surface movement of water. It is an undercurrent flow occasioned by the sinking of cold and heavy water. The water, on becoming cold, contracts and its density increases.
The density of the ocean water varies from place to place, a movement in the ocean waters occurs due to this.
A gyre is any large system of rotating surface ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis Effect; planetary vorticity along with horizontal and vertical friction, which determine the circulation patterns from the wind curl (torque).
Coriolis Effect is a deflection of moving objects when they are viewed in a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right. Coriolis Effect is causes ONLY in a rotating reference frame. The deflective force causes by the Coriolis Effect is caused Coriolis force. It has its own say in many geographical phenomena, most important being the deflection of the general direction of ocean currents.
Important Observations about Coriolis Force:
The currents flowing from equator towards the North Pole and from North Pole towards the equator are deflected to their right while the currents flowing north-south and south-north in the southern hemisphere are deflected towards their left
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The rotational force of the earth causes movement of ocean water near the equator in opposite direction to ‘the west to east rotation of the earth and thus equatorial currents are generated. These currents flow from east to west. Some ocean water moves in the direction of the rotation of the earth i.e. from west to east and thus counter equatorial currents are also formed.
