E.7. Movements Of Ocean Water

delete UPSC Sample Notes [English]

E.7. Movements Of Ocean Water

The movements of ocean water can be horizontal or vertical. The horizontal motion of oceanic water refers to the ocean currents and waves while vertical motion refers to tides.

Waves	Waves are formed by energy passing through water, resulting in it moving in a circular motion. Water particles travel only in a small circle as a wave passes. The Wind causes waves to travel in the ocean and the energy is released on coastlines. When the depth of water is less than half the wavelength of the wave, the wave breaks. A wave’s size and shape reveal its origin. Steep waves are fairly young ones and are probably formed by local wind. Slow and steady waves originate from faraway places, possibly from another hemisphere. Waves travel because the wind pushes the water body in its course while gravity pulls the crests of the waves downward.
Ocean Currents	Ocean currents are rivers in the oceans and represent a regular volume of water in a definite path and direction. The strength of the Current refers to the speed of the current. Forces that influence currents – Heating by solar energy Gravity Wind Coriolis force The difference in water density
Types Of Ocean Current	Surface currents – constitute about 10% of all the water in the ocean. These waters are the upper 400m of the ocean. They can be divided into – Cold currents – bring cold water into warm water areas. They are usually found on the west coast of the continents in low and middle latitudes. Eg. Peruvian current, Labrador current etc Warm Currents – Bring warm water into cold water areas and are usually observed on the east coast of constituents in the low and middle latitudes. Eg. Brazilian Current, Agulhas Current etc. Deep Water currents – make up the other 90% of the ocean Water.
Tides	The periodical rise and fall of the sea level once or twice a day, mainly due to the attraction of the sun and moon,is called a tide. Factors – The gravitational pull of the sun and moon Centrifugal force The tide-generating force is the difference between these two forces – The gravitational attraction of the moon and the centrifugal force.
Types Of Tides	The height of rising water varies appreciably depending upon the position of the sun and moon with respect to the earth. Spring tides – When the sun, the moon and the Earth are in a straight line – Tide will be higher. They occur twice a month, one during the full period and another during the new moon period. Neap tides– Sun and moon are perpendicular to each other. The forces of the sun and moon tend to counter one another. Tide will be low. Tidal flows are of great importance in navigation. These tides are also helpful in desilting the sediments and in removing polluted water from river estuaries.

[Image: Deep Water Circulations]

[Image: Types of Tides]