Chapter 3 – Hydrosphere | Class 10 School Geography Solution

Question 1

The regular movements of water from one part of the ocean to another are called :

1. tide
2. wave
3. ocean current
4. Tsunami

Answer

(c) Ocean current

Explanation:

The regular movement of water from one part of the ocean to another is called ocean current. Tides are the periodic rise and fall of sea levels caused by gravitational forces, waves are disturbances that travel through the surface of the water, and tsunamis are large ocean waves usually caused by underwater earthquakes or volcanic eruptions.

Question 2

The rise and fall of the surface of the ocean is called :

1. tide
2. wave
3. ocean current
4. Tsunami

Answer

(a) tide

Explanation:

The rise and fall of the surface of the ocean is called tide. Tides are caused by the gravitational forces of the Moon and the Sun acting on the Earth’s oceans. Waves are disturbances that travel through the surface of the water, ocean currents are the regular movements of water from one part of the ocean to another, and tsunamis are large ocean waves usually caused by underwater earthquakes or volcanic eruptions.

Question 3

The currents that flow from tropical areas towards the Polar regions are :

1. cold currents
2. both warm and cold current
3. warm currents
4. neither warm nor cold current

Answer

(c) Warm currents

Explanation:

The currents that flow from tropical areas towards the Polar regions are warm currents. These currents are generally warmer than the surrounding water and can have a significant impact on the climate of the regions they flow through. Cold currents, on the other hand, flow from polar regions towards the equator and are generally cooler than the surrounding water.

Question 4

Seasonal variation cause movements of ocean currents mainly in the :

1. Atlantic ocean
2. Indian ocean
3. Pacific ocean
4. Antarctic ocean

Answer

(c) Pacific Ocean

Explanation:

Seasonal variation can cause movements of ocean currents mainly in the Pacific Ocean. This is because the Pacific Ocean is the largest ocean on Earth, and its circulation is affected by seasonal changes in winds and temperature. The El Niño and La Niña phenomena, which have significant impacts on weather patterns around the world, are also associated with seasonal variations in the Pacific Ocean.

Question 5

The warm, occasional Pacific surface water along the coast of Peru is called :

1. El Nino
2. Gulf stream
3. North Atlantic drift
4. Labrador current

Answer

(a) El Nino

Explanation:

The warm, occasional Pacific surface water along the coast of Peru is called El Niño. It is a climate phenomenon that occurs every few years and involves the warming of the central and eastern tropical Pacific Ocean, which can have significant impacts on weather patterns around the world.

Question 6

The ocean currents get deflected to the right in the Northern Hemisphere due to :

1. Earth’s revolution
2. Earth’s rotation
3. Salinity
4. Temperature

Answer

(b) Earth’s rotation

Explanation:

The ocean currents get deflected to the right in the Northern Hemisphere due to Earth’s rotation. This phenomenon is known as the Coriolis effect, which causes moving objects, including ocean currents, to appear to veer to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Question 7

The periodic rise and fall in the level of oceans is called

1. tide
2. wave
3. ocean current
4. Tsunami

(a) Tide

Explanation:

The periodic rise and fall in the level of oceans is called tide. Tides are caused by the gravitational forces of the Moon and the Sun acting on the Earth’s oceans.

Question

1. Grand Bank is famous for commercial fishing.
2. Spring tides occur on full moon.
3. The moon is about 5 lakh 84 thousand km away from the earth.
4. Ocean currents deflect due to rotational movement of the earth.
5. Interval between two primary tides is 24 hours.
6. Secondary tide is the tide occuring at right angle to the primary tide.

Answer

1. True
2. True
3. False
   The actual distance is about 384,400 kilometers
4. True
5. False
   the interval between two consecutive high or low tides is roughly 12 hours and 25 minutes
6. True

Question

1. Due to rotation of the earth, ____ force acts upon the ocean currents.
2. All water bodies like oceans, seas, lakes and rivers of the earth’s surface are together called ____.
3. A very slow-moving ocean current is called a ____.
4. Cold currents flow from ____  region to ____ region.
5. The temperature of equatorial seas is ____ than that of polar seas.
6. Molting of ice can add  ____ making seawater less saline.

Answer

1. Due to rotation of the earth, Coriolis force acts upon the ocean currents.
2. All water bodies like oceans, seas, lakes and rivers of the earth’s surface are together called hydrosphere.
3. A very slow-moving ocean current is called a gyre.
4. Cold currents flow from polar region to equatorial region.
5. The temperature of equatorial seas is warmer than that of polar seas.
6. Melting of ice can add freshwater making seawater less saline.

Answer in word or words

Question 1

What do we call the high tidal wale near the moulin of a river?

Answer

The high tidal wave near the mouth of a river is called a tidal bore.

Question 2

What is the position of the moon called when it is nearest to the earth?

Answer

The position of the moon when it is nearest to the earth is called perigee.

Question 3

What is the distance of the moon from the earth at Apogee?

Answer

The distance of the moon from the Earth at apogee is about 405,500 kilometres.

Question 4

What do we call the situation when the sun, moon and earth are in a straight line?

Answer

When the sun, moon, and earth are in a straight line, it is called syzygy.

Question 5

What is the time interval between one primary and one secondary tide?

Answer

The time interval between one primary and one secondary tide can vary but is generally around 12 hours and 25 minutes.

Question 6

What are the highest high tides called?

Answer

The highest high tides are called spring tides.

Question

Answer

(1) Fog – (e) Increases density

(2) Surface currents – (a) Currents deflected to the left

(3) Lowest high tide – (b) Neap tide

(4) Salinity (High) – (c) Warm ocean currents

(5) Southern Hemisphere – (d) Cold ocean currents

Question 1

Classify ocean currents and write one characteristic of each.

Answer

Ocean currents can be classified into two main types based on their temperature:

Warm Currents:

• Characteristic: Warm ocean currents bring warm water from the equator to higher latitudes, warming coastal regions and influencing local climates. For example, the Gulf Stream in the North Atlantic warms the eastern coast of North America.

Cold Currents:

• Characteristic: Cold ocean currents transport cold water from polar regions to lower latitudes, cooling coastal areas and affecting local weather patterns. The California Current along the western coast of North America is an example of a cold current.

Question 2

How does shape of the coastline affect the movement of ocean currents?

Answer

The shape of the coastline can affect the movement of ocean currents by creating barriers and channels that alter the direction and speed of the currents. For example, a coastline with a large bay can cause the currents to circulate within the bay, while a narrow strait can increase the speed of the current.

Question 3

How does the melting of ice influence the movement of ocean currents?

Answer

The melting of ice can influence the movement of ocean currents by altering the salinity and density of the water. When ice melts, it adds freshwater to the ocean, which decreases the salinity and makes the water less dense. This can affect the formation of deep ocean currents, which are driven by differences in density.

Question 4

Why is there dense fog where cold and warm ocean currents meet?

Answer

Dense fog occurs where cold and warm ocean currents meet because the warm air above the warm current rises and cools as it meets the cold air above the cold current. This cooling causes the moisture in the air to condense into fog.

Question 5

Identify the winds influencing the currents of the northern part of Indian ocean?

Answer

The monsoon winds, including the Southwest monsoon and Northeast monsoon, are the primary winds that influence the currents of the northern part of the Indian Ocean. These winds cause the ocean currents to change direction twice a year, and the resulting currents are known as the Somali Current and the Indian Monsoon Current.

Question 6

What is tidal bore?

Answer

Tidal bore is a natural phenomenon that occurs when a high tide forms a wave that travels up a river or narrow bay against the direction of the river or bay’s current. This wave can be several meters high and can create strong currents and turbulence. The Qiantang River in China is famous for its tidal bore.

Answer the following questions

Question 1

Write the differences between primary and secondary tide.

Answer

Question 2

Why do warm ocean currents flow along the surface of the ocean?

Answer

Warm ocean currents flow along the surface of the ocean because of their lower density compared to the surrounding water. This lower density is due to their higher temperature, which reduces their solubility and increases their volume. As a result, warm ocean currents remain near the surface as they are less dense than the cold water underneath.

Question 3

Distinguish between spring tide and neap tide.

Answer

Question 4

How does climatic change affect the movement of ocean currents?

Answer

Climate change can affect the movement of ocean currents in several ways:

1. The melting of ice sheets can change the salinity of ocean water, affecting the density and circulation of ocean currents.
2. Changes in air temperature can alter wind patterns, which in turn can change the direction and strength of ocean currents.
3. Warmer air temperatures can cause warmer surface water, which can slow down or weaken ocean currents.
4. Climate change can cause changes in precipitation patterns, leading to changes in river outflows and the mixing of freshwater and saltwater, which can affect ocean currents.

Question 5

Why do we find commercial fishing banks at places where warm and cold currents meet each other?

Answer

Commercial fishing banks are found at places where warm and cold currents meet each other because the meeting point of these currents results in an increase in the concentration of plankton and other nutrients. Plankton serves as a food source for small fish, which in turn attracts larger fish and other marine animals. The mixing of the warm and cold currents creates a dynamic ecosystem that supports a diverse range of marine life, making it an ideal location for commercial fishing. The nutrient-rich water also helps to sustain the fish populations, making it easier for fishermen to catch them.

Solve the puzzle from the clues given

Clues:

Across

(1) All water bodies on the surface of the earth together form this.

(2) Lowest high tides.

(3) The straight-line configuration of the sun, moon and earth.

Down

(4) The periodic rise and fall of oceans and seas.

(5) The amount of salt in ocean water is this

(6) The rise and fall of ocean water form this

Answer

Across:

(1) Hydrosphere (2) Neap tide (3) Syzygy

Down:

(4) Tide (5) Salinity (6) Waves

Long answer or essay-type questions

Question 1

How do ocean currents originate or form?

Answer

Ocean currents can originate from various factors, including wind, temperature, salinity, and the Earth’s rotation. Winds blowing over the surface of the ocean can create surface currents, which are driven by the friction between the atmosphere and the ocean’s surface. Temperature and salinity differences between different parts of the ocean can also create density gradients, which in turn drive deep ocean currents. The rotation of the Earth also plays a role in creating ocean currents, as it causes the Coriolis effect, which deflects currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. In some cases, ocean currents can also be influenced by geological features such as continental shelves and seamounts.

Question 2

Explain the formation of tides.

Answer

Tides are formed by the gravitational pull of the moon and the sun on the Earth’s oceans. The moon’s gravity is much stronger than the sun’s, so it has a greater effect on the tides. As the earth rotates, the moon’s gravitational force causes a bulge of water on the side of the earth closest to the moon. This creates a high tide.

As the earth rotates, the bulge of water moves with the moon, causing another high tide on the opposite side of the earth. These are known as the primary tides. As the moon moves in its orbit around the earth, the location of the bulge of water changes, causing the tides to shift.

When the moon is at its closest point to the earth (perigee) or its farthest point (apogee), the gravitational pull is even stronger or weaker, respectively, causing higher or lower tides. When the sun, moon, and earth are in a straight line, the gravitational pull is also stronger, causing higher tides, known as spring tides.

When the sun and moon are at right angles to each other, their gravitational forces partially cancel each other out, causing lower tides, known as neap tides. This cycle repeats approximately every 24 hours and 50 minutes.

Question 3

How are tides caused?

Answer

Tides are caused by the gravitational pull of the moon and the sun on the Earth’s oceans. The gravitational force of the moon is stronger on the side of the Earth facing the moon, causing a high tide. The gravitational force of the moon is weaker on the opposite side of the Earth, causing another high tide. The areas in between experience a low tide as water are pulled away from these regions. The gravitational pull of the sun also affects tides, though to a lesser extent than the moon. When the gravitational force of the sun and moon are aligned, spring tides occur, creating the largest difference between high and low tides. When the gravitational force of the sun and moon are perpendicular, neap tides occur, creating the smallest difference between high and low tides. The rotation of the Earth also affects tides, creating a 24-hour cycle between high and low tides.

Question 4

Why does time differ at the rate of 24 hours and 52 minutes between two primary tide at any particular place?

Answer

The time difference between two primary tides at any particular place is not exactly 24 hours due to the complex interactions between the Moon, Sun, and Earth. The Moon’s gravity pulls the ocean towards it, creating a high tide on the side of the Earth facing the Moon and a corresponding bulge on the opposite side. As the Earth rotates, this bulge moves around the planet, causing a high tide to occur approximately every 12 hours and 25 minutes.

Question 5

What are the effects of ocean currents on earth?

Answer

Ocean currents have various effects on the Earth, including:

1. Climate regulation: Ocean currents regulate the Earth’s climate by transporting warm and cold water around the planet, which affects atmospheric temperature and precipitation patterns.
2. Marine life distribution: Ocean currents affect the distribution of marine life by carrying nutrients, oxygen, and larvae across the ocean, creating habitats and affecting migration patterns.
3. Navigation: Ocean currents are used for navigation by ships and boats, especially for trade and transportation, and can also affect the time and fuel required for travel.
4. Coastal erosion and deposition: Strong ocean currents can cause erosion or deposition of sediment along coastlines, affecting the stability of beaches and shorelines.
5. Economic impact: Ocean currents affect fishing industries and commercial activities, as well as energy production through the use of ocean currents for generating electricity.

Question 6

Discuss what are Apogee and Perigee.

Answer

Apogee refers to the point in the Moon’s orbit when it is farthest away from the Earth. This distance can vary, but it is usually around 405,500 kilometres. During this time, the Moon appears smaller in the sky and its gravitational pull on the Earth is weaker, resulting in weaker tidal forces.

Perigee, on the other hand, refers to the point in the Moon’s orbit when it is closest to the Earth. This distance also varies, but it is usually around 363,300 kilometres. During this time, the Moon appears larger in the sky and its gravitational pull on the Earth is stronger, resulting in stronger tidal forces.

Question 7

What are the effects of tides?

Answer

Tides have several effects on the Earth and its environment, some of which are:

1. Erosion and sedimentation: Tides can cause erosion of the coastline and deposit sediment in certain areas, which can impact the shape and formation of coastlines.
2. Navigation: Tides affect the depth of water in oceans, bays, and estuaries, making navigation easier or more challenging depending on the tide level.
3. Marine life: Tides impact marine life by bringing in nutrients and food sources and affecting the distribution of organisms and their breeding and feeding behaviours.
4. Energy production: Tides can be harnessed for energy production through tidal power generation systems.
5. Climate: Tides play a role in regulating the Earth’s climate by affecting the mixing of ocean water and the transport of heat and nutrients around the globe.

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