UPSC STATIC QUIZ – Geography : 9 February 2024

Solution: c)

Near the equator the ocean water is about 8 cm higher in level than in the middle latitudes. This causes a very slight gradient and water tends to flow down the slope.

Solar energy makes current warm or cold and decides their circulatory patterns.

Solution: c)

Surface currents are generated largely by wind. Their patterns are determined by wind direction, Coriolis forces from the Earth’s rotation, and the position of landforms that interact with the currents.

Currents may also be generated by density differences in water masses caused by temperature and salinity variations.  These currents move water masses through the deep ocean—taking nutrients, oxygen, and heat with them.

Occasional events also trigger serious currents. Huge storms move water masses. Underwater earthquakes may trigger devastating tsunamis.

Solution: b)

Salinity at the surface increases by the loss of water to ice or evaporation, or decreased by the input of fresh waters, such as from the rivers. Salinity at depth is very much fixed, because there is no way that water is ‘lost’, or the salt is ‘added.’

It is a well-known fact that the maximum temperature of the oceans is always at their surfaces because they directly receive the heat from the sun and the heat is transmitted to the lower sections of the oceans through the process of convection. It results into decrease of temperature with the increasing depth, but

the rate of decrease is not uniform throughout. The temperature falls very rapidly up to the depth of 200 m and thereafter, the rate of decrease of temperature is slowed down.

Solution: b)

Statement 1 is incorrect.

Salinity changes with depth, but the way it changes depends upon the location of the sea. Salinity at the surface increases by the loss of water to ice or evaporation, or decreased by the input of fresh waters, such as from the rivers. Salinity at depth is very much fixed, because there is no way that water is ‘lost’, or the salt is ‘added.’ There is a marked difference in the salinity between the surface zones and the deep zones of the oceans. The lower salinity water rests above the higher salinity dense water. Salinity, generally, increases with depth and there is a distinct zone called the halocline, where salinity increases sharply.

Solution: b)

Statement 3 is incorrect.

• All waters in nature, whether rain water or ocean water, contain dissolved mineral salts. Salinity is the term used to define the total content of dissolved salts in sea water. It is calculated as the amount of salt (in gm) dissolved in 1,000 gm (1 kg) of seawater. It is usually expressed as parts per thousand (o/oo) or ppt. Salinity is an important property of sea water. Salinity of 24.7 o/oo has been considered as the upper limit to demarcate ‘brackish water’.

• In the land locked Red Sea, salinity is as high as 41o/oo, while in the estuaries and the Arctic, the salinity fluctuates from 0 – 35 o/oo, seasonally.
• The salinity variation in the Pacific Ocean is mainly due to its shape and larger areal extent.
• The highest salinity is recorded between 15° and 20° latitudes.