TEST 06: GEOGRAPHY

Syllabus: pressure belts, movement of ocean water

1. Consider the following statements regarding the atmospheric pressure:

1. The weight of the column of air at a given place and time is called air pressure or atmospheric pressure.

2. Atmospheric pressure is measured by an instrument called Thermometer.

3. Atmospheric pressure is measured as force per unit area and the unit used for measuring pressure is called millibar.

Which of the above statements is/are correct?

a. 2 only

b. 1 and 3

c. 2 and 3

d. 1, 2 and 3

2. Air pressure decreases with:

a.The decrease in altitude

b.Increase in altitude

c.The decrease in density of air

d.Decrease in the temperature of air

3. Consider the following statements regarding the air temperature and the air pressure on various regions on earth:

1. Air pressure is low in equatorial regions and it is higher in Polar Regions.

2. There is an inverse relationship between air temperature and air pressure.

3. Low air pressure in equatorial regions is due to the fact that hot air ascends there with a gradual decrease in temperature causing thinness of air on the surface.

Which of the above statements is/are correct?

a. 2 only

b.1 and 3

c.2 and 3

d.1, 2 and 3

4. Earth’s rotation generates which of the following force?

a.Centrifugal force

b.Centripetal force

c.Kinetic Force

d.Static force

5.Consider the following statements regarding the equatorial low-pressure belt:

1. The equatorial low-pressure belt extends from the equator to 100N and 100S latitudes.

2. The equatorial low-pressure belt is called doldrums (the zone of calm) due to excessive heating horizontal movement of air is absent here and only conventional currents are there.

Which of the above statements is/are correct?

a. 2 only

b. 1 and 2

c. 2 and 3

d. 1, 2 and 3

6. Which of the following forces affect the Velocity and Direction of Wind:

1. Pressure Gradient Force

2. Frictional Force

3. Coriolis Force

Identify the correct statements:

a. 1 & 3 only

b. 2 & 3 only

c. All are correct

d. 2 only

7. Consider the following Statements regarding Inter Tropical Convergence Zone (ITCZ)

1. The air at the Inter Tropical Convergence Zone (ITCZ) rises because of convection caused by high insolation and a high pressure is created.

2. The easterlies from either side of the equator converge in the Inter Tropical Convergence Zone (ITCZ).

Identify the correct statements:

a. 1 only

b. 2 only

c. All are correct

d. None

8. Consider the following Statements regarding Fronts:

1. When two different air masses meet, the boundary zone between them is called a front.

2. The fronts occur in middle latitudes and cause the air to rise to form clouds and cause precipitation.

3. There are four types of fronts: (a) Cold; (b) Warm; (c) Stationary; (d) Occluded.

4. If an air mass is fully lifted above the land surface, it is called the stationery front.

Identify the correct statements:

a. 1, 2 & 3 only

b. 2, 3 & 4 only

c. All are correct

d. 2 & 4 only

9. Consider the following Statements regarding condensation of water vapour:

1. When the moisture is deposited in the form of water droplets on cooler surfaces of stones, grass blades and plant leaves, it is known as dew.

2. Frost forms on cold surfaces when condensation takes place below freezing point.

3. The difference between the mist and fog is that mist contains more moisture than the fog.

Identify the correct statements:

a. 1 & 3 only

b. 2 & 3 only

c. All are correct

d. 2 only

10. Consider the following Statements regarding Divisions of the Ocean Floors:

1. Canyons and trenches are observed in continental shelves.

2. Seamount is a mountain with pointed summits, rising from the seafloor that reaches the surface of the ocean.

Identify the correct statements:

a. 1 only

b. 2 only

c. All are correct

d. None

11. Consider the following statements regarding the motion of waves and water molecules on the sea surface:

1. Water particles only travel in a small circle as a wave passes.

2. When the depth of water is less than half the wavelength of the wave, the wave breaks.

3. The largest waves are found in enclosed sea.

4. Most of the waves are caused by the wind driving with the water.

Which of the above statements is true?

a. 1 and 2

b. 3 and 2

c. 2 and 4

d. 3 and 4

12. Which of the following factors influence the movement of ocean water?

1. Temperature

2. Salinity of Ocean

3. Density of Ocean Water

4. Wind System

5. Coriolis Force

Choose the correct codes:

a. 1,2 and 3

b. 2 and 3

c. 1,2,3 and 5

d. All of the above

13. Tides and surges are the two different types of movement of ocean water. Consider the following statements in this regard:

1. Movement of water caused by meteorological effects is called surges.

2. The periodical rise and fall of the sea level mainly due to the attraction of the sun and the moon is called a tide.

3. Surges are also regular like tides.

Which of the above statements is true?

a. Only 1

b. 1 and 2

c. Only 2

d. Only 3

14. Which of the following is not the relevant use of tidal movement?

a.Tidal flows are of great importance in navigation.

b. Tides help in the development of coral reefs.

c. Tides are also helpful in desilting the sediments and in removing polluted water from river estuaries.

d. Tides are used to generate electrical power.

15. Consider the following types of tides based on their frequency of occurrence and their height:

1. In Diurnal tide, there is only one high tide and one low tide during each day.

2. Mixed tides generally occur along the west coast of South-East Asia.

3. In Semi-diurnal tide, successive high or low tides of the same height occur.

Which of the above statements is true?

a. Only 1

b. 1 and 3

c. Only 2

d. 1, 2 and 3

Answers

1.B

• The atmosphere is held on the earth by the gravitational pull of the earth. A column of air exerts weight in terms of pressure on the surface of the earth. The weight of the column of air at a given place and time is called air pressure or atmospheric pressure. Atmospheric pressure is measured by an instrument called barometer. Nowadays, Fortin’s barometer and Aneroid barometer I are commonly used for measuring air pressure.
• Atmospheric pressure is measured as force per unit area. The unit used for measuring pressure is called millibar. Its abbreviation is ‘mb’. One millibar is equal to the force of one gram per square centimetre approximately.

2.B

• The columnar distribution of atmospheric pressure is known as vertical distribution of pressure. Air pressure decreases with increase in altitude but it does not always decrease at the same rate.
• Dense components of the atmosphere are found in its lowest parts near the mean sea level. The temperature of the air, amount of water vapour present in the air and gravitational pull of the earth determines the air pressure of a given place and at a given time.
• Since these factors are variable with change in height, there is a variation in the rate of decrease in air pressure with an increase in altitude.

3. B

• The earth is not heated uniformly because of unequal distribution of insolation, differential heating and cooling of land and water surfaces. Generally, there is an inverse relationship between air temperature and air pressure. The higher the air temperature, the lower is the air pressure.
• The fundamental rule about gases is that when they are heated, they become less dense and expand in volume and rise. Hence, air pressure is low in equatorial regions and it is higher in polar regions. Along the equator lies a belt of low pressure known as the “equatorial low or doldrums”.
• Low air pressure in equatorial regions is due to the fact that hot air ascends there with a gradual decrease in temperature causing thinness of air on the surface. In polar region, cold air is very dense hence it descends and pressure increases.

4. A

• The earth’s rotation generates centrifugal force. This results in the deflection of air from its original place, causing a decrease in pressure. It is believed that the low-pressure belts of the sub-Polar Regions and the high-pressure belts of the sub-tropical regions are created as a result of the earth’s rotation.
• The earth’s rotation also causes convergence and divergence of moving air. Areas of convergence experience low pressure while those of divergence have high pressure.

5. B

• The sun shines almost vertically on the equator throughout the year. As a result, the air gets warm and rises over the equatorial region and produce equatorial low pressure.
• This belt extends from the equator to 100N and 100S latitudes. Due to excessive heating horizontal movement of air is absent here and only conventional currents are there. Therefore this belt is called doldrums (the zone of calm) due to the virtual absence of surface winds.
• These are the regions of convergence because the winds flowing from sub-tropical high-pressure belts converge here. This belt is also known as-Inter Tropical Convergence Zone (ITCZ).

6.C

• The air in motion is called wind. The wind blows from high pressure to low pressure. The wind at the surface experiences friction. In addition, rotation of the earth also affects the wind movement.
• The force exerted by the rotation of the earth is known as the Coriolis force. Thus, the horizontal winds near the earth surface respond to the combined effect of three forces – the pressure gradient force, the frictional force and the Coriolis force.

7. B

• The air at the Inter Tropical Convergence Zone (ITCZ) rises because of convection caused by high insolation and a low pressure is created.

8.A

• When two different air masses meet, the boundary zone between them is called a front. The process of formation of the fronts is known as frontogenesis. There are four types of fronts: (a) Cold; (b) Warm; (c) Stationary; (d) Occluded
• When the front remains stationary, it is called a stationary front.
•  When the cold air moves towards the warm air mass, its contact zone is called the cold front, whereas if the warm air mass moves towards the cold air mass, the contact zone is a warm front. If an air mass is fully lifted above the land surface, it is called the occluded front.

9. C

10.A

• Seamount is a mountain with pointed summits, rising from the seafloor that does not reach the surface of the ocean.

11. A

• Waves are actually the energy, not the water as such, which moves across the ocean surface. Water particles only travel in a small circle as a wave passes. The Wind provides energy to the waves. The Wind causes waves to travel in the ocean and the energy is released on shorelines. The motion of the surface water seldom affects the stagnant deep bottom water of the oceans.
• As a wave approaches the beach, it slows down. This is due to the friction occurring between the dynamic water and the sea floor and when the depth of water is less than half the wavelength of the wave, the wave breaks. The largest waves are found in the open oceans. Waves continue to grow larger as they move and absorb energy from the wind.
• Most of the waves are caused by the wind driving against water. When a breeze of two knots or less blows over calm water, small ripples form and grow as the wind speed increases until white caps appear in the breaking waves.

12. D

• The ocean water is dynamic. Its physical characteristics like temperature, salinity, density and the external forces like of the sun, the moon and the winds influence the movement of ocean water. The horizontal and vertical motions are common in ocean water bodies. The horizontal motion refers to the ocean currents and waves. The vertical motion refers to tides.

13.B

• The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. Movement of water caused by meteorological effects (winds and atmospheric pressure changes) are called surges. Surges are not regular like tides. The study of tides is very complex, spatially and temporally, as it has great variations in frequency, magnitude and height.
• The moon’s gravitational pull to a great extent and to a lesser extent the sun’s gravitational pull, are the major causes for the occurrence of tides. Another factor is the centrifugal force, which is the force that acts to counterbalance the gravity.

14. B

• Tides are caused by the earth, moon and sun positions which are known accurately and hence the tides can be predicted well in advance. This helps the navigators and fishermen plan their activities. Tidal flows are of great importance in navigation.
• Tidal heights are very important, especially harbours near rivers and within estuaries having shallow ‘bars’ at the entrance, which prevent ships and boats from entering into the harbour. Tides are also helpful in desilting the sediments and in removing polluted water from river estuaries. Tides are used to generate electrical power especially in Canada, France, Russia, and China.

15. B

• Tides vary in their frequency, direction and movement from place to place and also from time to time. Tides may be grouped into various types based on their frequency of occurrence in one day or 24 hours or based on their height.
• Tides based on Frequency Semidiurnal tide: The most common tidal pattern, featuring two high tides and two low tides each day. The successive high or low tides are approximate of the same height.
• Diurnal tide: There is only one high tide and one low tide during each day. The successive high and low tides are approximate of the same height.
• Mixed tide: Tides having variations in height are known as mixed tides. These tides generally occur along the west coast of North America and on many islands of the Pacific Ocean.
• Tides based on the Sun, Moon and the Earth Positions: The height of rising water (high tide) varies appreciably depending upon the position of sun and moon with respect to the earth.