Tuesday, 17 October 2023

Ocean and Man


 *Ocean And Man*


1. What is the difference between bay and strait


 ➡️ The portion of the sea surrounded by land on three sides is called a bay.


➡️ The narrow stretch of sea between two landmasses is known as strait. 


2. Differentiate between ocean and sea


➡️  Ocean is defined as the body of salt water covering much of the Earth (eg: Indian ocean)


➡️ Sea is the portion of an ocean close to the land. (Eg: The Arabian Sea is a part of the Indian 

Ocean)


3. Name the deepest point in the Pacific Ocean


 ✅ Challenger Deep (11034m)


4. Name the deepest point in the Atlantic Ocean


✅ Puerto Rico trench (8618 m)


5. Which mountain range exists along the middle of the Atlantic ocean.


✅ The Mid Atlantic ridge


6. Write any three features of the Antarctic Ocean


➡️ The ocean surface is frozen


➡️ Also known as the 'southern ocean'


➡️  Total area: 32 lakh sq.km


7. Name the smallest ocean


✅ The Arctic Ocean


8. Differentiate between Islands and peninsula


➡️  Islands are land surrounded by sea on all sides.


➡️ The landmasses surrounded by sea on three sides are called peninsula


9. What are the important characteristics of sea water?


➡️ Temperature, salinity, and density


10. What are the different factors for the variation in temperature over different latitudinal zones?


➡️  Variation in the amount of insolation received on the earth.


➡️ The ocean currents and winds


11. What is salinity? How is it expressed? 


➡️  The concentration of salt content in sea water is known as salinity. 


➡️ Grams of salt present in 1000 grams of water


12. Salinity is not uniform across oceans. Give reasons ? 


➡️ More in land-locked seas 


➡️ Increases in areas of high evaporation 


➡️ Decreases in areas where snow melt water reaches in large quantity 


➡️  Decreases at river mouths 


➡️ Heavy rainfall leads to reduction in salinity


13. The density of sea water is not uniform everywhere. Why? 


➡️ Due to the variations in salinity and temperature of sea water. 


➡️  Density decreases as temperature increases; and it increases as salinity increases.


*Ocean and Man*


1. What are the different movements of sea water?


*Waves ,tides, and ocean currents*


2. Define the following.


➡️ Sea waves


The up and down motion of the water along the surface of the sea.


➡️ Wave crest


The summit of the wave

Trough

The bottom part of the wave


➡️ Wave length


The distance between two adjacent crests.


➡️ Wave height


The vertical distance between the crest and the trough.


3. What is the reason for waves?


The friction exerted by winds on the ocean surface.


4. What are the measures taken to prevent damage and to protect the lives of people living in the coastal areas?


■ Depositing boulders along the seashore.


■ Construction of interlocking concrete structures (Pulimuttu)


◻️ Planting of mangroves.


■ Sand bars (solution by nature to protect the shores from sea surges)


5. What are tides? Which are the two types of tides?


Tides are the periodic rise and fall of water level in the ocean.

The rise in the level of ocean water is the *high tide*.


The lowering of the water level is known as the *low tide*.


6. What are the reasons for tides?


The gravitational pull exerted by the moon and the sun The centrifugal force due to the earth's rotation.


7. Explain with the help of a figure how high tides and low tides.



➡️ The water level on the part of the earth facing the moon rises.


➡️ The rise in water level due to the gravitational pull exerted by the moon leads to high tide.


➡️ The centrifugal force due to the earth's rotation is the reason for the rise in water level at the opposite side Due to the draining of water towards the tidal regions the water level goes down.


➡️ The fall of water level is known as low tide.


8. Explain Spring tides and neap tides with the help of figures.


➡️ The sun, moon, and earth come in a straight line on full moon and new moon days.


➡️ The tidal force will be intense due to the combined influence of sun and moon.


➡️ As a result the tides formed on these days will

be stronger. These are known as *spring tides*.


➡️ After seven days from the full moon and new moon days.


➡️ The moon and the sun will be at an angular distance of 90° from the earth

The tides caused are weak.


 Such tides are known as *neap tides*.


9. Write the Effects of tides


■ The debris dumped along the sea shores and ports are washed off to

the deep sea.


◻️The formation of deltas is disrupted due to strong tides.


◻️Brackish water can be collected in salt pans during high tides.


◻️The fishermen make use of the tides for going and returning from the sea in catamarans.


 ◻️Tidal energy can be used for power generation.


◻️Ships can be brought to shallow harbours during high tides.



10. Differentiate between Warm currents and cold currents.


➡️ Warm currents are the currents that flow from the tropical or subtropical regions towards the polar or sub polar regions.


➡️ Cold currents are the currents that flow from the polar or the sub polar regions towards the tropical or subtropical region.


11. Write the effects of ocean currents.


➡️ Influence the climate of coastal regions.


➡️ Fog develops in the regions where warm and cold currents meet.


➡️ The regions where the warm and cold currents meet provide favourable conditions for the growth of fish.


12. Oceans are useful to man in different ways. Justify this statement.


➡️ Influencing our climate.


➡️Providing mineral deposits.


➡️ Helping power generation.


➡️ Providing source of food.


➡️ Drinking water from the sea. 


➡️ Providing job opportunities. 


➡️ Possibilities for tourism.

Ocean transport. 

 

13. Name the oil field started in 1974 in Mumbai.


■ Mumbai High

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