Flash-Cards-for-IAS-Prelims-2018-Geo-Day-5
70 Days WAR Plan

Day#5 Static Flash Cards Physical & World Geography [70 Days WAR Plan]

Active Volcanoes; Theory of sea-floor spreading; Abyssal Plains; Planetary winds; ‘Normal lapse rate’; Venus; Mediterranean climate zones; Soil of Tundra Region; Pole star; ‘Salt Weathering’;
By IT's Core Team
March 27, 2019

 

 

 

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.

 

 

 

Why the pole star appears to be stationary from the Earth?

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Why the pole star appears to be stationary from the Earth?

Answer:

The pole star appears to be stationary from the Earth, because it is situated close to the direction of the axis of rotation of the Earth. The angle of Pole star decreases towards the Equator. At the equator, the angle of pole star is 0 degree and its angle is 90 degree at the poles.

About Pole star:

  • Pole star, also called North Star, the brightest star that appears nearest to either celestial pole at any particular time.
  • Pole star or polar star is a name of Polaris in the constellation Ursa Minor, after its property of being the naked-eye star closest to the Earth’s north celestial pole.

 

 

 

Give some examples of the active Volcanoes around the world.

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Answer:

  • A volcano is called an active volcano if the materials mentioned are being released or have been released out in the recent past.

Below are some of the examples of the active Volcano around the world:

Mount Sinabung, Indonesia

  • Located in North Sumatra, the volcano roared back to life in 2010, with alerts being raised in 2013, 2014 and most recently in January 2018.
  • It spewed huge plumes of smoke and started oozing lava, so much so that authorities permanently warned people against going near it.

Mt. Cleveland, Alaska, US

  • Located in the Aleutian Islands, this volcano has erupted at least 22 times in the last 230 years. It last erupted on April 16, 2016.

Mount Etna, Italy

  • At 10,925 feet (3,330 meters), Mount Etna is Europe’s tallest active volcano and has been erupting almost continuously for about half a million years.
  • Its height keeps changing as volcanic material collects during eruptions and crater walls collapse subsequently.
  • In May 2016, the volcano shot spectacular bursts of lava into the sky spewing forth from its Voragine Crater as it erupted.

Mt. Merapi, Indonesia

  • Active for at least 10,000 years, this volcano which is also known as the “Mountain of Fire,” rates high in terms of lava flow.
  • A 2010 eruption killed more than hundred people and left 320,000 more without homes.

Mount Agung, Indonesia

  • Since mid-November 2017, the Bali volcano has been rumbling and spewing smoke and lava, in its first explosion in more than 50 years. With a growing lava dome, Agung is still active.

 

 

 

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.

 

 

 

Venus is commonly known as morning star but at times also known as evening star. Why?

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Answer:

Venus is regarded as morning and evening star because of the positional difference of east and west while revolving around the sun when looked from earth.

venus planet inside

  • Venus is earth’s nearest planetary neighbour. It is the brightest planet in the night sky.
  • Sometimes Venus appears in the eastern sky before sunrise. Sometimes it appears in the western sky just after sunset. Therefore, it is often called a morning or an evening star, although it is not a star.
  • Venus has no moon or satellite of its own. Rotation of Venus on its axis is somewhat unusual. It rotates from east to west while the Earth rotates from west to east. That is the reason why the sun rises in the east and sets in the west.
  • When the Venus is on the east side of the earth, the Venus would rise before the sun. For the sun to rise, the earth would have to rotate further by some degrees, which is equal to the elongation of the planet. Therefore, the Venus would be visible on the eastern horizon a few hours before sunrise. Therefore, it is called the morning star.
  • Similarly after a few months, when the Venus is on the west of the earth in its orbit, the sun would rise before the Venus and hence it would not be visible in the morning due to the sun’s brilliance.
  • In the evening, when the sun sets, the Venus will still be above the observer’s horizon and will be visible to the observer as the evening star. For Venus to set, the earth has to rotate a few more degrees on its axis.

 

 

 

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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Answer:

Abyssal-Plains-info

  • 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 evidence 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.
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  • Jayansh Singh

    Please correct the definitions of positive and negative lapse rates given in the Flash Card as apparently they’ve been mistakenly swiped. Positive lapse rate is when the temperature decreases with increasing altitude.

    • Dear Jayansh, you are right but the error was due to the facts mentioned in the NIOS. It caused confusion. The links are https://www.nios.ac.in/media/documents/313courseE/L33.pdf

      Majority of sources available on net are mentioning that Positive lapse rate is when the temperature decreases with increasing altitude. One thing which caused confusion here is that Positive lapse rate occurs in stratosphere and thermosphere. In both stratosphere and thermosphere, temperature rises with increasing altitude which is called Positive lapse rate. That’s why error here!!!

      • Jayansh Singh

        Yes, that’s correct. Thank you for clarifying.

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