Physical geography Sem 1

 

Physical geography Sem 1 

Section A 

Very short answer type questions (30words)

Q1.1.Define core of earth?  

2 What are natural levees?

3 Define cyclone?

4 Define diurnal tide?

5 What is Playa?

6 Explain Karst topography?

SECTION – B (Short Answer Questions)

 any four questions.

 200 words.

4 × 3 = 12 Marks

Q2.Make a note on elastic rebound theory?

Q3.Describe chemical weathering?

Q4.What is Horse Latitude?

Q5.Make a note on convectional rainfall?

Q6.Mention the sources of ocean deposits?

SECTION – C (Long Answer Questions)

 any two questions.

500 words.

2 × 6 = 12 Marks

Q7.Explain the nature and scope of physical geography?

Q8.Describe the atmospheric pressure belts in detail?

Q9.Explain oceanic salinity in detail?

VMOU Kota – Physical Geography 

(Semester 1) Assignment Answers 

SECTION A — Very Short Answer Type (30 words each)

Q1(1). Define core of the Earth.

The core is the innermost layer of the Earth, made mainly of iron and nickel. It has two parts—solid inner core and liquid outer core—and generates Earth’s magnetic field.

Q1(2). What are natural levees?

Natural levees are raised embankments formed along riverbanks. They are created when a river floods and deposits heavier sediments near its banks, naturally building up a ridge.

Q1(3). Define cyclone.

A cyclone is a large, low-pressure system with strong rotating winds moving inward. It forms over warm oceans and produces heavy rainfall, storms, and powerful winds.

Q1(4). Define diurnal tide.

A diurnal tide is a tidal pattern in which only one high tide and one low tide occur each day (approximately every 24 hours).

Q1(5). What is a Playa?

A playa is a shallow, dry lake bed found in deserts. It forms when water temporarily collects and then evaporates, leaving behind fine sediments and salts.

Q1(6). Explain Karst topography.

Karst topography is a landscape formed by the dissolution of limestone. It includes features like caves, sinkholes, underground streams, and disappearing rivers created by chemical weathering.

SECTION B — Short Answers (Any 4, 200 words each)

Q2. Make a note on elastic rebound theory.

The Elastic Rebound Theory explains the cause of earthquakes. It was proposed by H.F. Reid after the 1906 San Francisco earthquake. According to this theory, rocks along a fault line are under continuous tectonic stress caused by the movement of Earth’s lithospheric plates. As the pressure builds, the rocks on both sides of the fault bend and deform elastically. They store energy much like a stretched rubber band.

When the stress becomes greater than the strength of the rocks, the rocks suddenly break and slip along the fault. This sudden release of stored energy is felt as an earthquake. The ground then “rebounds” to its original undeformed position, though the rocks may no longer fit perfectly together.

The theory also explains why earthquakes occur repeatedly along certain faults. Stress continues to accumulate until another break happens. Important points include:

Stress builds slowly over time.

Rocks deform elastically.

Sudden rupture releases energy as seismic waves.

The crust returns to its new balanced position.

Thus, the Elastic Rebound Theory provides a scientific understanding of how and why earthquakes happen along faults.

Q3. Describe chemical weathering.

Chemical weathering is the breakdown of rocks through chemical changes in their minerals. Unlike physical weathering, which only breaks rocks into smaller pieces, chemical weathering alters the rock’s composition. It occurs mostly in warm, humid climates where water is abundant.

Major processes of chemical weathering include:

1. Solution: Certain minerals, especially salts and limestone, dissolve in water. This forms caves, sinkholes, and karst features.

2. Oxidation: Minerals combine with oxygen, especially iron-bearing rocks, producing rust-like colors. It weakens rocks and leads to the formation of soil.

3. Hydration: Minerals absorb water and expand, causing the rock to crack and soften.

4. Hydrolysis: Water reacts with minerals like feldspar to form clay. This is one of the most important processes in soil formation.

5. Carbonation: Rainwater mixed with carbon dioxide forms weak carbonic acid that dissolves limestone and marble.

Chemical weathering is crucial because it forms soil, influences landforms, and releases nutrients for plants. It is most active where temperature and rainfall are high.

Q4. What is Horse Latitude?

Horse Latitudes are subtropical high-pressure belts located around 30° North and 30° South of the equator. These regions are known for calm conditions, clear skies, and very little wind. The air here descends, creating stable atmospheric conditions.

Because of sinking air, the region is dry and is responsible for many world deserts such as the Sahara, Arabian, and Australian deserts. Historically, sailing ships often got stuck here because winds were weak. According to one popular explanation, during long, windless voyages, sailors had to throw horses overboard to conserve water—hence the name “Horse Latitude.”

These zones are important because they influence global wind patterns, desert formation, and weather conditions.

Q5. Make a note on convectional rainfall.

Convectional rainfall occurs when the Earth’s surface becomes heated by the sun. The warm surface heats the air, causing it to rise rapidly. As the air rises, it cools and condenses to form clouds. When condensation continues, heavy rainfall occurs.

This type of rainfall is most common in the equatorial regions during the afternoon. It also occurs in tropical areas during summers. Convectional rainfall is usually heavy, short-lived, and accompanied by thunder and lightning because rising air creates strong vertical currents.

The process can be summarized as:

Sun heats the ground

Ground heats the air

Warm air rises

Rising air cools

Clouds form

Heavy rainfall occurs

Convectional rainfall is important for agriculture in tropical regions and contributes to dense vegetation in equatorial forests.

Q6. Mention the sources of ocean deposits.

Ocean deposits are materials that accumulate on the ocean floor. Their main sources are:

1. Terrigenous deposits: These come from land, carried by rivers, wind, glaciers, and coastal erosion. Examples include sand, clay, silt, and volcanic ash.

2. Biogenous deposits: Formed from remains of marine organisms such as shells, corals, bones, and microscopic plankton. They include calcareous and siliceous ooze.

3. Hydrogenous deposits: Created by chemical precipitation from seawater. Examples are manganese nodules, phosphates, and metal-rich deposits.

4. Volcanic deposits: Ash, lava fragments, and other materials from underwater volcanoes or eruptions on land that fall into the sea.

These deposits help in understanding ocean history, marine life, and mineral resources.

SECTION C — Long Answers (Any 2, 500 words each)

Q7. Explain the nature and scope of physical geography.

Physical geography is a major branch of geography that studies the natural features and processes of the Earth. Its central focus is on understanding the physical environment in which humans live. Physical geography examines landforms, climate, soils, vegetation, water bodies, and natural hazards. It explains how these elements interact and shape the Earth’s surface.

The nature of physical geography is scientific and systematic. It uses observation, measurement, mapping, and analysis to understand natural processes. It draws knowledge from geology, meteorology, hydrology, biology, and environmental science. Physical geography studies both the past and present conditions of the Earth to predict future changes. It is also dynamic, because natural processes like earthquakes, volcanoes, erosion, and climate change continuously modify the Earth.

The scope of physical geography is very wide and includes several subfields:

1. Geomorphology: The study of landforms such as mountains, valleys, plateaus, plains, rivers, glaciers, and deserts. It examines processes like erosion, weathering, and tectonic forces that shape the Earth’s crust.

2. Climatology: The study of climate and weather patterns. It includes temperature, rainfall, winds, atmospheric pressure, and climate change.

3. Hydrology: The study of water bodies, such as oceans, lakes, rivers, groundwater, and the hydrological cycle.

4. Biogeography: The study of distribution of plants and animals across different regions and environments.

5. Soil Geography: The study of soil types, their formation, composition, and distribution.

6. Environmental Geography: It examines the interactions between humans and the natural environment, including resource use and environmental problems.

Physical geography also plays an important role in practical applications. It helps in disaster management, agricultural planning, urban development, and environmental conservation. Understanding climate patterns assists in predicting droughts, floods, and cyclones. Knowledge of landforms guides construction projects, transportation routes, and water management.

In conclusion, physical geography provides a scientific foundation for understanding the Earth’s natural systems. Its broad scope helps explain environmental processes, human-environment relationships, and the functioning of our planet as a whole.

Q8. Describe the atmospheric pressure belts in detail.

The Earth has a system of global pressure belts formed due to uneven heating of the Earth’s surface. These belts influence wind patterns, climate zones, and weather systems. There are seven major pressure belts arranged from the equator to the poles.

1. Equatorial Low-Pressure Belt (Doldrums):

Located around the equator (0°–5° N and S), this belt experiences intense heating. Warm air rises, creating low pressure. It is a region of calm winds, heavy rainfall, and thunderstorms.

2. Subtropical High-Pressure Belts (Horse Latitudes):

Found at 30° N and S, these belts are created as air that rises at the equator descends. The descending air creates clear skies and dry climates. Many deserts lie in this region.

3. Subpolar Low-Pressure Belts:

Located around 60° N and S, these belts form where warm tropical air meets cold polar air. This convergence produces low pressure and unstable weather. Storms and cyclones are common.

4. Polar High-Pressure Belts:

Found at the poles (90° N and S), extremely cold temperatures cause air to sink, creating high pressure. The air moves outward toward lower latitudes as polar winds.

Why These Belts Form:

Uneven heating of the Earth

Coriolis force caused by Earth’s rotation

Seasonal shifts of the sun

Movement of air masses

Shifting of Pressure Belts:

Due to the Earth’s tilt, pressure belts shift northward in summer and southward in winter. This affects monsoon winds and seasonal climates.

Overall, the pressure belts create a global circulation system that drives wind patterns, ocean currents, and climate zones.

Q9. Explain oceanic salinity in detail.

Oceanic salinity refers to the amount of dissolved salts in seawater. It is measured in parts per thousand (‰). Average ocean salinity is about 35‰, meaning 35 grams of salt per kilogram of seawater. The salts mainly include sodium chloride, magnesium, calcium, potassium, and sulphates.

Factors affecting salinity:

1. Evaporation: High evaporation increases salinity, especially in warm tropical regions.

2. Precipitation: Heavy rainfall dilutes seawater, lowering salinity.

3. River Inflow: Freshwater from rivers reduces salinity in coastal areas.

4. Temperature: Warm water increases evaporation, raising salinity.

5. Ice melting: Melting glaciers reduce salinity; freezing increases it by removing freshwater.

6. Ocean currents: Warm currents raise salinity, cold currents lower it.

Distribution:

Equatorial regions have moderate salinity due to high rainfall.

Tropical regions (20°–30° latitudes) have highest salinity because of strong evaporation and low rainfall.

Polar regions have low salinity due to melting ice and low evaporation.

Landlocked seas, like the Dead Sea, have extremely high salinity.

Importance of Salinity:

Affects density of seawater, which influences ocean circulation.

Helps determine marine life distribution.

Influences climate and weather patterns.

Plays a role in formation of currents.

Thus, oceanic salinity is an essential element of oceanography and helps regulate Earth’s climate system.