Very Short Answer Questions

Q1. What are streams of water moving in a definite pattern called?
Ans: Streams of water moving in a definite pattern are called Ocean Currents.

Q2. What are the giant waves caused by earthquakes on ocean floors called?
Ans: Tsunami giant waves caused by earthquakes on ocean floors.

Q3. What are the three movements of ocean water?
Ans: Waves, Tides and Ocean Currents are the three movements of ocean water.

Q4. Define the term Salinity.
Ans: The amount of salt in the ocean water is called salinity.

 

Short Answer Questions

Q1. What is the hydrological cycle?
Ans. The process by which water continually changes its form and circulates between lithosphere, atmosphere and hydrosphere is known as the Water Cycle or the Hydrological Cycle. It is a never ending process.

Q2. Is water a renewable resource?
Ans. Yes, water is called as a renewable resource because it can be used again and again. Water changes its form, due to heat water evaporates, when cools it condenses to form clouds and then through precipitation water comes back to the earth, this is a continuous process.

Q3. What does the word 'Tsunami' means?
Ans. An earthquake, a volcanic eruption or underwater landslides can shift large amounts of ocean water. As a result a huge tidal wave called tsunami originates.
Tsunami is a Japanese word that means "Harbour waves" as the harbours get destroyed whenever there is tsunami. The term "Tsunami" has been derived from: - "Tsu" – Harbour and "Nami" – Waves. Meaning huge tidal waves.

Q4. Explain why warm ocean currents are less dense than cold ocean currents.
Ans. Warm ocean currents are less dense than the cold ocean currents because the warm ocean currents originate near the equator and move towards the poles. Due to high temperature, moisture content in the air becomes very less making the warm currents rise the temperature over land surface. Whereas, cold ocean currents blow from Poles towards the equator. Here the temperature is less and moisture content is more, making these currents more dense than the warm currents

 

Long Answer Questions

Q1. What are the different types of tides and how are they caused? How are tides useful?
Ans. The tides are broadly classified into two types: Spring Tides and Neap Tides.
• During the full moon and new moon days, the sun, the moon and the earth are in the same line and the tides are highest. These tides are called spring tides. It is high tide when water covers much of the shore by rising to its highest level.
• But when the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides. It is low tide when water falls to its lowest level and recedes from the shore.

Tides help us in the following ways:
• High tides help in navigation. This helps the ships to arrive at the harbour more easily.
• The high tides also help in fishing.
• Tides are also helpful in generating electricity.

Q2. How are ocean currents different from waves? Which factors are responsible for giving rise to ocean currents?
Ans.

Factors affecting the Ocean Currents: -
1. Planetary Winds.
2. Rotation of the Earth
3. Variation in the temperature
4. Density of ocean water
5. Shapes of the coastlines

Q3. Suggest measures to conserve water. When do we celebrate 'World Water Day'?
Ans. Some of the important ways to conserve water are:
1. Decrease of water pollution: Discharge of untreated sewage, agriculture chemicals & industrial effluents.
2. Proper irrigation method.
(a) Sprinklers can be used to irrigate very large area.
(b) Drip irrigation can be used in dry regions, where evaporation is very high.
3. Water Harvesting Method: This water can be used for cleaning, washing, gardening, etc.
4. Water conservation in the home.
• Check faucets and pipes for leaks.
• Check your toilets for leaks.
• Use your water meter to check for hidden water leaks.
• Install water-saving shower heads and low-flow faucet aerators.
• Put plastic bottles or float booster in your toilet tank.
• Insulate your water pipes.
• Take shorter showers.
• Turn off the water after you wet your toothbrush.
• Use your dishwasher and clothes washer for only full loads.
• When washing dishes by hand, don't leave the water running for rinsing.

'World Water Day' is celebrated on 22 March every year.

Q4. Give reasons:
(a) Ocean currents are important. How?
(b) Tides are very useful. How?
Ans.
(a) Following are the importance of ocean currents:
• Warm and cold currents help in controlling the climatic conditions of the world.
• Ocean currents help in navigation.
• ocean currents are important to the distribution of the world's sea life.
• Ocean currents also act as the convectional source of energy.

(b) Tides are very useful, following are the different ways:
• High tides help in navigation. This helps the ships to arrive at the harbour more easily.
• The high tides also help in fishing.
• Tides are also helpful in generating electricity.

Q5. The ocean currents are broadly divided into warm and cold currents. Why are they called so? What makes them warm and cold?
Ans. The ocean currents are broadly divided into warm and cold currents. These currents get influence by the temperature conditions of an area. The warm ocean currents originate near the equator and move towards the poles. Warm currents rise the temperature over land surface.
Whereas, the cold currents carry water from polar or higher latitudes to tropical or lower latitudes. Cold currents reduces the temperature of the coastal areas.
Movement of these currents make them warm or cold. The general circulation of ocean currents is clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere.

 

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