Earthquake waves are basically of two types — body waves and surface waves.
Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the earth. Hence, the name body waves. The body waves interact with the surface rocks and generate new set of waves called surface waves.
Surface waves move along the surface. The velocity of waves changes as they travel through materials with different densities. The denser the material, the higher is the velocity. Their direction also changes as they reflect or refract when coming across materials with different densities. There are two types of body waves. They are called P and S-waves.
P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves’. The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials.
S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials.
There exist some specific areas where the waves are not reported. Such a zone is called the ‘shadow zone’. The zone between 105° and 145° from epicentre was identified as the shadow zone for both the types of waves. The entire zone beyond 105° does not receive S-waves. Hence, the shadow zone of S-wave is much larger than that of the P-waves.

The earthquake events are scaled either according to the magnitude or intensity of the shock. The magnitude scale is known as the Richter scale. The magnitude relates to the energy released during the quake. The magnitude is expressed in numbers, 0-10.
The intensity scale is named after Mercalli, an Italian seismologist. The intensity scale takes into account the visible damage caused by the event. The range of intensity scale is from 1-12.

Sea floor spreading theory was given by “Hess”.
Main points of his theory are as follows:
(i) All along the mid-oceanic ridges, volcanic eruptions are common and they bring huge amounts of lava to the surface in this area.
(ii) 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 polarit and are the youngest. The age of the rock increases as one moves away from the crest.
(iii) The ocean crust rocks are much younger than the continental rocks. The age of rocks in the oceanic crust is nowher more than 200 million years old. Some of the continental rock formations are as old as 3,200 million years.
(iv) 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, nowher was the sediment column found to be older than 200 million years.

Both the statements are incorrect:

The insolation received by the earth is in short waves forms and heats up its surface. The earth after being heated itself becomes a radiating body and it radiates energy to the atmosphere in long wave form. This energy heats up the atmosphere from below. This
process is known as terrestrial radiation. The long wave radiation is absorbed by the atmospheric gases particularly by carbon dioxide and the other green house gases. Thus, the atmosphere is indirectly heated by the earth’s radiation.

The atmosphere in turn radiates and transmits heat to the space. Finally the amount of heat received from the sun is returned to space, thereby maintaining constant temperature at the earth’s surface and in the atmosphere.

The pattern of planetary winds largely depends on:
(i) latitudinal variation of atmospheric
heating;
(ii) emergence of pressure belts;
(iii) the migration of belts following apparent path of the sun;
(iv) the distribution of continents
and oceans;
(v) the rotation of earth.
The pattern of the movement of the planetary winds is called the general circulation of the
atmosphere.

In mountainous regions, during the day the
slopes get heated up and air moves upslope
and to fill the resulting gap the air from the
valley blows up the valley. This wind is known as the valley breeze. During the night the
slopes get cooled and the dense air descends
into the valley as the mountain wind. The cool air, of the high plateaus and ice fields draining into the valley is called katabatic wind. Another type of warm wind occurs on the leeward side of the mountain ranges. The moisture in these winds, while crossing the mountain ranges condense and precipitate. When it descends down the leeward side of the slope the dry air gets warmed up by adiabatic process. This dry air may melt the snow in a short time.
Valley breeze is also known as anabatic wind.

The systems developing in the mid and high latitude, beyond the tropics are called the middle latitude or extra tropical cyclones. Extra tropical cyclones form along the polar front.
The extra tropical cyclone differs from the
tropical cyclone in number of ways:
(i) The extra tropical cyclones have a clear frontal system which is not present in the tropical cyclones.
(ii) They cover a larger area and can originate over the land and sea. Whereas the tropical cyclones originate only over the seas and on reaching the land they dissipate.
(iii) The extra tropical cyclone affects a much larger area as compared to the tropical cyclone.
(iv) The wind velocity in a tropical cyclone is much higher and it is more destructive.
(v) The extra tropical cyclones move from west to east but tropical cyclones, move from east to west.

The North Sea, in spite of its location in higher latitudes, records higher salinity due to more saline water brought by the North Atlantic Drift. Baltic Sea records low salinity due to influx of river waters in large quantity.
The Mediterranean Sea records higher salinity due to high evaporation. Salinity is, however, very low in Black Sea due to enormous fresh water influx by rivers. The low salinity trend is observed in the Bay of Bengal due to influx of river water. On the contrary, the Arabian Sea shows higher salinity due to high evaporation and low influx of fresh water.

Canaries current is the cold current in North Atlantic Ocean.
Falkland current is the cold current in South Atlantic Ocean.
Kuroshio current is a warm current in North Pacific Ocean.
Agulhas current is a warm current in South Indian Ocean.

Orographic Rain
When the saturated air mass comes across a mountain, it is forced to ascend and as it rises, it expands; the temperature falls, and the moisture is condensed. The chief characteristic of this sort of rain is that the windward slopes receive greater rainfall. After giving rain on the windward side, when these winds reach the other slope, they descend, and their temperature rises. Then their capacity to take in moisture increases and hence, these leeward slopes remain rainless and dry. The area situated on the leeward side, which gets less rainfall is known as the rain-shadow area. It is also known as the relief rain.
Heavy rainfall with thunder and lightening is a characteristic feature of convectional type of rainfall.

Normally, temperature decreases with increase in elevation. It is called normal lapse rate. At times, the situations is reversed and the normal lapse rate is inverted. It is called

Inversion of temperature. Inversion is usually of short duration but quite common nonetheless. A long winter night with clear skies and still air is ideal situation for inversion. The heat of the day is radiated off during the night, and by early morning hours, the earth is cooler than the air above. Over polar areas, temperature inversion is normal throughout the year.

The mid-day sun never shines overhead on any latitude beyond the Tropic of Cancer and the Tropic of Capricorn. The angle of the sun’s rays goes on decreasing towards the poles. As such, the areas bounded by the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere, and the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere, have moderate temperatures. These are, therefore, called Temperate Zones.
Areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere, are very cold. It is because here the sun does not rise much above the horizon. Therefore, its rays are always slanting and provide less heat. These are, therefore, called Frigid Zones (very cold).

There are three types of mountains- Fold Mountains, Block Mountains and the Volcanic Mountains.
The Himalayan Mountains, Aravalis in India, the Alps, The Appalachians in North America and the Ural mountains in Russia are examples of fold mountains.
The Rhine valley and the Vosges mountain in Europe are examples of block mountains.
Mt.Kilimanjaro in Africa and Mt.Fujiyama in Japan are examples of volcanic mountains.

The uppermost layer over the earth’s surface is called the crust. It is the thinnest of all the layers. It is about 35 km. on the continental masses and only 5 km. on the ocean floors. The main mineral constituents of the continental mass are silica and alumina. It is thus called sial (si-silica and al-alumina). The oceanic crust mainly consists of silica and magnesium; it is therefore called sima (si-silica and ma-magnesium).

EI-Nino is a complex weather system that appears once every three to seven years, bringing drought, floods and other weather extremes to different parts of the world.
The system involves oceanic and atmospheric phenomena with the appearance of warm currents off the coast of Peru in the Eastern Pacific and affects weather in many places including India. EI-Nino is merely an extension of the warm equatorial current which gets replaced temporarily by cold Peruvian current or Humbolt current. This current increases the temperature of water on the Peruvian coast by 10°C. This results in:

(i) the distortion of equatorial atmospheric circulation;
(ii) irregularities in the evaporation of sea water;
(iii) reduction in the amount of planktons which further reduces the number of fish in the sea.

From the given places, Bhopal lies closest to Tropic of Cancer at 23.2599° N, 77.4126° E. Allahabad is 25.4358° N, 81.8463° E, Patna is 25.5941° N, 85.1376° E and Imphal is 24.8170° N, 93.9368° E.

In India, iron and steel industry has developed taking advantage of raw materials, cheap labour, transport and market. All the important steel producing centres such as Bhilai, Durgapur, Burnpur, Jamshedpur, Rourkela, Bokaro are situated in a region that spreads over four states — West Bengal, Jharkhand, Orissa and Chhattisgarh. Bhadravati and Vijay Nagar in Karnataka, Vishakhapatnam in Andhra Pradesh, Salem in Tamil Nadu are other important steel centres utilising local resources.

Turkey is bordered on its northwest by Greece and Bulgaria; north by the Black Sea; northeast by Georgia; east by Armenia, the Azerbaijani exclave of Nakhchivan and Iran; southeast by Iraq; south by Syria and the Mediterranean Sea; and west by the Aegean Sea.

The order of seas from West to East is:
Black sea, Caspian Sea, Aral Sea and Arafura Sea.

The order of rivers from North to South is as follows:
Penganga
Godavari
Krishna
Tungabhadra