Flash Card

LAKSHYA-75 [Day-34] Static Flash Cards for IAS Prelims 2020

Geothermal energy; Cyclonic or frontal rain; The Distribution of Volcanoes in the World; Evidence supporting the theory of sea-floor spreading; Abyssal Plains; Planetary winds; ‘Normal lapse rate’; Mediterranean climate zones; Characteristics of the soil of Tundra Region; ‘Salt Weathering’;
By IASToppers
April 11, 2020

What do you mean by the term ‘Salt Weathering’?

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Answer:

  • Weathering refers to the process by which rock is broken down over time. It is called “salt weathering” when salt is involved in the process.
  • There are three distinct types of weathering: chemical weathering, physical weathering, and biological weathering. Salt weathering falls under the category of physical weathering.
  • No chemical alteration of rock constituents is involved in salt weathering.
  • The salt derives from an external source (capillary rising ground water, eolian origin, sea water along rocky coasts, atmospheric pollution). Salt weathering is favoured by dry conditions, such as are found in warm and cold (arctic) arid climates.
  • Salt weathering occurs when a saline solution gets into cracks or pores in rock. If the temperature changes enough for the ice to crystallize, it will expand in the crack, and may fracture the rock.
  • The more porous a material is, the more susceptible it will be to the effects of salt weathering.
  • Salt weathering is primarily a concern in marine areas where the presence of the ocean ensures a high level of salt in water vapor. Salt weathering also tends to happen in climates that are hot and dry.
  • Salt weathering (salt damage, salt decay) also occurs on buildings and monuments in arid climates as well as under dry microclimatic conditions in humid climates.

What are the characteristics of the soil of Tundra Region?

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Answer:

  • Soil of Tundra Region are not rich in nutrients and minerals except for when it can obtain nutrients from animal droppings.
  • Freezing and thawing landscape that creates unique patterns in the ground. In summer water is collected underground. This water then freeze that pushes the soil upward into a small hill called Pingo.
  • It is usually very cold in the tundra. It is formed at high latitudes. Tundra soils are generally frozen and are classifed as Gelisols. These regions are too cold for the decomposition of organic matter.
  • Humus gathers in cold climates as the growth of bacteria is slow.
  • There are varieties of mosses, lichens, shrubs and trees, and animals in this type of region.
  • Layers of peat developed in this region along with mechanically broken materials.
  • The soil is frozen thus plants aren’t able to grow their roots deep into the ground.

Mediterranean climate zones are associated with the five large subtropical high-pressure belts of the oceans. Which are they?

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Answer:

The five large subtropical high-pressure belts of the oceans which are associated with the Mediterranean climate zones are:

  1. Azores High
  2. South Atlantic High
  3. North Pacific High
  4. South Pacific High
  5. Indian Ocean High

About Mediterranean climate:

  • It has dry summers and mild, rainy winters. It is located on the western sides of continents, between roughly 30 and 45 degrees north and south of the equator.
  • Mediterranean climate occurs around Mediterranean sea, along the west coast of continents in subtropical latitudes between 30° – 40° latitudes e.g. — Central California, Central Chile, along the coast in south eastern and south western Australia. These areas come under the influence of sub-tropical high in summer and westerly wind in winter.
  • Monthly average temperature in summer is around 25° C and in winter below 10°C. The annual precipitation ranges between 35 – 90 cm.

In context of physical geography, what does the term ‘Normal lapse rate’ mean?

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Answer:

  • The environmental temperature decreases with increasing height of atmosphere. It decreases at the rate of 10C at the height of 165 metre. This is called Normal lapse rate.
  • The increase of temperature with the increase of altitude is known as positive lapse rate while the decrease in temperature with the increase of altitude is known as negative lapse rate.
  • Positive lapse rate occurs in stratosphere and thermosphere. Negative lapse rate occurs in troposphere and mesosphere.
  • Normal lapse rate varies with height, season, latitude, time of day, location and other factors.
  • It is important to note that the actual lapse rate of temperature does not always show a decrease with altitude.

The pattern of planetary winds largely depends on which factors?

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Answer:

What are Planetary winds?

  • Planetary or permanent winds blow from high pressure belts to low pressure belts in the same direction throughout the year.
  • They blow over vast area of continents and oceans.
  • They are easterly and westerlies and polar easterlies.
  • Planetary winds blow in the same direction throughout the year, while the other types of winds get modified due to certain reasons.
  • The pattern of the movement of the planetary winds is called the general circulation of the atmosphere. The general circulation of the atmosphere also sets in motion the ocean water circulation which influences the earth’s climate.

Pattern of planetary winds largely depends on:

  1. Latitudinal variation of atmospheric heating.
  2. Emergence of pressure belts.
  3. The migration of belts following apparent path of the sun.
  4. The distribution of continents and oceans.
  5. The rotation of earth

What do you know about the Abyssal Plains?

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  • Abyssal Plains are extensive plains that lie between the continental margins and mid-oceanic ridges.
  • The abyssal plains are the areas where the continental sediments that move beyond the margins get deposited.
  • They cover a major portion of the ocean floors between the depths of 3000m to 6000m.
  • Abyssal plains are as irregular as the continental plains with submarine plateaus, hills, guyots, and seamounts.
  • The floor of the abyssal plain is covered by sediments which are formed from the remains of living things are called Oozes. Oozes can be seen in those seas which favour an abundant growth of organisms.
  • Another type of sediments is red clay which is of volcanic origin or made up of tiny particles brought by wind and rivers.

Several types of evidences supported Hess’s theory of sea-floor spreading. Mention some of these evidences.

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Answer:

Evidence supporting the theory of sea-floor spreading:

  • It was realised that all along the mid-oceanic ridges, volcanic eruptions are common and they bring huge amounts of lava to the surface in this area.
  • The rocks equidistant on either sides of the crest of mid-oceanic ridges show remarkable similarities in terms of period of formation, chemical compositions and magnetic properties. Rocks closer to the mid-oceanic ridges have normal polarity and are the youngest. The age of the rocks increases as one moves away from the crest.
  • The ocean crust rocks are much younger than the continental rocks. The age of rocks in the oceanic crust is nowhere more than 200 million years old. Some of the continental rock formations are as old as 3,200 million years.
  • The sediments on the ocean floor are unexpectedly very thin. Scientists were expecting, if the ocean floors were as old as the continent, to have a complete sequence of sediments for a period of much longer duration. However, nowhere was the sediment column found to be older than 200 million years.
  • The deep trenches have deep-seated earthquake occurrences while in the mid-oceanic ridge areas, the quake foci have shallow depths.

What are the advantages and disadvantages of Geothermal energy?

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Solution:

The slow decay of radioactive particles in the earth’s core, a process that happens in all rocks, produces geothermal energy.

Enrich Your Learning:

Geothermal energy

  • Geothermal energy, form of energy conversion in which heat energy from within Earth is captured.
  • Geothermal energy is a renewable energy source because heat is continuously produced inside the earth.
  • People use geothermal heat for bathing, to heat buildings, and to generate electricity.

Geothermal energy use can be divided into three categories:

  • Direct-use applications,
  • Geothermal heat pumps (GHPs), and
  • Electric power generation.

Advantages:

  • It can be extracted without burning a fossil fuel such as coal, gas, or oil.
  • Geothermal fields produce only about one-sixth of the carbon dioxide that a relatively clean natural-gas-fueled power plant produces.
  • Binary plants release essentially no emissions.
  • Unlike solar and wind energy, geothermal energy is always available, 365 days a year.
  • It’s also relatively inexpensive; savings from direct use can be as much as 80 percent over fossil fuels.
  • Geothermal energy can be used as an efficient heat source in small end-use applications such as greenhouses, but the consumers have to be located close to the source of heat.  
  • The capital of Iceland, Reykjavik, is heated mostly by geothermal energy.
  • Geothermal energy has a major environmental benefit because it offsets air pollution that would have been produced if fossil fuels were the energy source.
  • Geothermal energy has a very minor impact on the soil – the few acres used look like a small light-industry building complex.  
  • Since the slightly cooler water is reinjected into the ground, there is only a minor impact, except if there is a natural geyser field close by.  

Disadvantages:

  • The main concern is the release of hydrogen sulfide, a gas that smells like rotten egg at low concentrations.
  • Another concern is the disposal of some geothermal fluids, which may contain low levels of toxic materials.
  • Although geothermal sites are capable of providing heat for many decades, eventually specific locations may cool down.

The volcanoes named St. Helena, Cape Verde Islands and the Canary Islands are located in which region of the world: (a) The Great Rift valley of Africa OR (B) Mid-Atlantic Region OR (c) Pacific Ring of Fire

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Answer:

Mid-Atlantic Region

Enrich Your Learning:

The Distribution of Volcanoes in the World:

  • Most known volcanic activity and the earthquakes occur along converging plate margins and mid-oceanic ridges.
  • The major regions of volcanic distributions are as follows:

Pacific Ring of Fire:

  • Circum-Pacific region, popularly termed the ‘Pacific Ring of Fire’, has the greatest concentration of active volcanoes.
  • Volcanic belt and earthquake belt closely overlap along the ‘Pacific Ring of Fire’. It is estimated to include two-thirds of the world’s volcanoes.

Mid-Atlantic Region:

  • The Mid-Atlantic Region coasts has comparatively fewer active volcanoesbut many dormant or extinct volcanoes.
  • Examples are Helena, Cape Verde Islands and the Canary Islands. But the volcanoes of Iceland and the Azores are active.

The Great Rift valley of Africa:

  • In Africa some volcanoes are found along the East African Rift Valley. Kilimanjaro and Mt. Kenya are extinct volcanoes.
  • The only active volcano in West Africa is Cameroon.

Mediterranean Region:

  • Volcanoes of the Mediterranean region are mainly associated with the Alpine folds.
  • Example, Mt. Vesuvius, Mt. Stromboli (known as the Light House of the Mediterranean Sea).

Other Regions:

  • Elsewhere in the interiors of continents of Asia, North America and Europe active volcanoes are rare. There are no volcanoes in Australia.

Volcanoes in India:

  • There are no volcanoes in the Himalayan region of India.
  • However, Barren Island, lying 135 km north-east of Port Blair became active in 1991 and 1995.
  • However, the other volcanic island in Indian Territory is Narcondam (Andaman and Nicobar Islands) It is probably extinct. Its crater wall has been completely destroyed.

Cyclonic rainfall is associated with fronts which form due to collision of different air masses. Right OR Wrong?

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Answer:

Right

Enrich Your Learning:

Cyclonic or frontal rain:

  • It is type of rainfall that independent of relief or convection. It is purely associated with cyclonic activitywhether in the temperate regions (depressions) or tropical regions (cyclones).
  • Basically it is due to the convergence (meeting) of two different air masses with different temperaturesand other physical properties. As cold air is denser, it tends to remain close to the ground.
  • In ascent, Pressure decreases, the air expands and cools, condensation takes place and light showers called cyclonic or frontal rain occur.
  • The heavier and colder air masses eventually push up the warmer and lighter air and the sky is clear again.

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Daily Current Flash Cards 2020 Prelims 2020
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