Geography (Part-4) (CDS-Solved Paper)

The primary effect of the Earth’s rotation is the phenomenon of day and night. The rotation of the Earth about its axis in an anti-clockwise direction (when viewed from over the North Pole) gives us the impression that the Sun rises in the East and sets in the West.

Our heavenly view, in particular that of the night sky, likewise reveals a panorama that moves from East to West. An additional effect is that of spin or rotation placed on weather systems by what is called. ‘Coriolis effect’.

Guinea current : Guinea, West
Coast of Africa
Oyashio current : East Coast of Russia
Canaries current : Canary Islands, West of Africa
Kuroshio current : East Coast of Japan

The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until is eventually merges with space. The atmospheric layers in sequence are as follows

1. The troposphere is the first layer above the surface and contains half of the Earth’s atmosphere. Weather occurs in this layer.

2. Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.

3. Meteors or rock fragments burn up in the mesosphere.

4. The thermosphere is a layer with auroras. It is also where the space shuttle orbits.

5. The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

Nagaland became the 16th State of the Indian Union on 1st December,1963.

Meghalaya was previously part of Assam, but on 21st January, 1972, the districts of Khasi, Garo and Jaintia hills became the new State of Meghalaya.

Sikkim became the 22nd State of the Indian Union on 15th May, 1975 and the monarchy was abolished

Arunachal Pradesh was granted statehood on 20th February, 1987.

Plate tectonic is a scientific theory describing the large scale motion of seven large plates and the movements of a large number of smaller plates of the Earth’s lithosphere.

The lithosphere is the rigid outermost shell of a planet (the crust and upper mantle), is broken into tectonic plates. Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere each topped by its own kind of crust.

Tectonic plates are able to move because the Earth’s lithosphere has greater mechanical strength than the underlying asthenosphere (viscous, weak, ductile region of upper mantle of the Earth). Plato boundaries are the edges where two plates meet.

Most geologic activities, including volcanoes, earthquakes and mountain building occurs at plate boundaries. Divergent plate boundaries are area where plate move away from each other forming either mid-oceanic ridges or rift valley. Earthquakes are common at mid-ocean ridges.

A convergent plate boundary is an area where two or more lithosphere collide. When oceanic crust converges with continental crust, the denser oceanic plate plunges beneath the continental plate.

This process called subduction, occurs at the oceanic trenches. The entire region is called subduction zone. This zone has a lot of intense earthquakes and volcanic eruptions. The subducting plates cause melting in the mantle.

Wind is a natural movement of any velocity especially, the Earth’s air or the gas surrounding a planet in natural motion horizontally. There are mainly three factors that affect the wind direction.

They are atmospheric pressure, coriolis effect and topography. One of the prim drivers of wind direction is atmospheric pressure. Winds flow generally from high pressure to low pressure.

The other factors which play an important role is the coriolis effect. In coriolis effect, winds, though are partly shunted off almost courses between high and low pressure of the Earth by the rotation of Earth. Topography variations may affect the wind direction.

This factor does not operate exclusively of pressure influence. In the present, question option (a) seems to be right answer when we follow the general rule of wind direction which flows from high pressure to low pressure area.

India relies excessively on ground water resources, which accounts for over 60 per cent of irrigated area and 85% of drinking water supplies.

It is estimated that over 70% of India’s foodgrain production now comes from irrigated agriculture in which ground water plays an important role. The large scale exploitation of groundwater is done with the help of tube-wells.

Easy availability of electricity and poor maintenance of tanks were the main reason for the growth of tube-well irrigation in India. The green revolution technology has been one of the driving force for the groundwater use in India.

The adoption of new high yielding variety seeds and the accompanying use of fertilisers provided great benefits, and the gains were the best with irrigation. Huge investments were undertaken for surface water irrigation projects to provide irrigation water over vast areas.

Electricity supply expanded in rural areas making pumping of groundwater easy and economical. The large alluvial tracts in the India-Ganga Brahmaputra Plains extending from Punjab in went to Assam in the East alongwith coastal plains, constitutes one of the must potential groundwater reservior.

MONEX or monsoon experiment was a part of the Global Atmospheric Research Programme (GARP) and coincided with the First GARP Global Experiment (FGGE) in 1979.

MONEX was a field project developed to provide needed information on the processes that drive the large scale monsoon in order to better predict monsoons and their impact on human life.

There are two distinct monsoon system affecting India and South-East Asia so MONEX was divided into two components : summer and winter. The main focus area of experiments were South China Sea, Bay of Bengal, Arabian sea etc.

If Himalayas did not exist then North India plain would have been much cooler in winter, because they prevent the cold polar winds coming from Siberia from entering India and thus keep the country relatively warm during winter months.

In the Northern hemisphere, the Winter Solstice occurs on 22nd December, when the Sun shines directly over the Tropic of Capricorn, the Summer Solstice occurs on 21st June, when the Sun shines directly over the Tropic of Cancer.

In the Southern hemisphere, the winter and summer solstices are reversed. On 21st March and 23rd September, the Sun shines directly overhead the Equator. So, half part of all latitudes
receives sunlight.

Hence, the duration of day and night is equal everywhere. These two positions are referred to as Equinoxes means
equal days and nights. 21st March, is called Vernal Equinox and 23rd
September is called Autumnal Equinox.