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Correct Answer is : (a) Earth

Correct Answer is : (c) 71

The energy or heat received on earth or any other planet from the sun is called insolation.

(d) 8848 meters

(c) 840 meters

When the temperature of oceanic water is studied on the latitudinal basis, it is considered as the Horizontal Distribution of Ocean Temperature.

The highest place on the earth is Mt. Everest (8848 meters) and the deppest place is Mariana Trench (11033 meters).

Correct Answer is : (b) Fathom

(b) 3808 meters

There is about 4.10 million tonnes of salt in one cubic km. of sea water.

In the main salts found in the sea water, sodium chloride, magnesium chloride, magnesium sulphate, calcium sulphate, potassium sulphate, calcium carbonate and t magnesium bromide are included.

Terrestrial parts are found in the form of India in the north of the Indian Ocean, Africa in its west and Australia in its south – east.

The oceans in descending order as per their area are Pacific Ocean, Atlantic Ocean, Indian Ocean and Arctic Ocean.

A land form is a feature on the earth’s surface that is a part of the terrain. The surface physical shapes are studied under the land forms.

The salinity is found to be the highest in tropical regions due to the high temperature, prevailing warm and dry winds, excessive evaporation, lack of rainfall and lesser availability of clean water.

Adequate information is not available about this ocean located on the North Pole because most of its part remains covered with snow for most of the year. Its place of submergence is very wide. Many islands are found on this ocean, in which Barents, Hope, Spitsbergen, Novaya, etc. are the major ones. In the seas found in this ocean, the Norway Sea, Laptev Sea, East Siberian Sea and Greenland Sea are the major ones. Many sub-merged ridges are found here.

In the north of the Indian Ocean, part of Gondwana Land, Peninsular India, Plateau of Africa, western part of Australia continental land are present. Many troughs are found in this ocean which include Arabian Trough, Mauritius Trough, Andaman Trough, Oman Trough, Naital Trough, etc. Many ridges are also found in this ocean which include Socotra – Chagos Ridge, Chagos Ridge, Sachlis Ridge, St. Paul Ridge, Amsterdam Ridge, Madagascar Ridge and Indian Antarctica Ridge.

In the gulfs found in this ocean, the Bay of Bengal, Gulf of Aden, Persian Gulf and Gulf of Thailand are the major ones. Many islands are found in this oceanic part in which Lakshadweep Island, Andaman and Nicobar Islands Group,Madagascar Island, Zanzibar and Reunion Islands are included. Sunda is the main deep of this ocean.

Pacific Ocean extends over 18000 km. in width from east to west, and 16740 km in length from north to south.

The physical forms of the upper surface of the earth is called the Relief. In this, parts of the earth’s surface with heights and depths: mountain, valley, plain, plateau etc. physical landscapes are included. The word relief is used to express the inequalities and variations in the physical profile of the earth’s surface.

The factors affecting the oceanic temperature are as follows:

1. Latitude. 

2. Inequality in the distribution of water and land. 

3. Duration of day.

4. Clear atmosphere. 

5. Distance of the earth from the sun. 

6. Number of sunspots. 

7. Ocean Currents.

Among all these factors, in context to the latitudinal status, the temperature decreases on moving towards the poles from the equator. Inequality in the distribution of water and land also affects the temperature, length (duration) of the day (sunshine hours) is also a temperature controller.

The increase or decrease in the amount of dust particles and water vapour in the atmosphere also plays an important role in the temperature distribution. The more or less distance of the earth from the sun, the increase or decrease in the number of sunspots, the ocean currents being cold or warm, also affect the temperature of the ocean water.

Ahead of the continental shelf, the slope of ocean floor becomes abruptly steep. The biggest feature of these slopes is that they may extend upto a depth of 3600 to 9100 meters. Here, the deposit of alluvial soil is found very less. Due to the lack of light and nutritional substances, the amount of vegetation and sea creatures is found to be less. These slopes are found on 8.5 % part of the total area of oceans. Their slope is between 2 degree to 5 degree.

Salinity is obtained in ocean water mainly from the rivers, which carry 16 million tonnes of salt from the terrestrial regions every year and deposit them in the oceans. Salinity is also obtained from waves, winds and volcanic eruptions.

The Ocean Bottom is classified mainly into four relief features:

1. Continental Shelf: It refers to the submerged coast. Thus, those parts of the continents which remain submerged in ocean are called the Continental Shelf and whose maximum depth is considered to be 100 fathom. 

2. Continental Slope: Ahead of the continental shelf, the slope of ocean floor becomes abruptly steep. It extends upto a depth of 3600 to 9100 meters. 

3. Deep Sea Plain: The slope becomes very gentle on the end of the continental slope and the marine plain starts, which is called the Deep Sea Plain. 

4. Oceanic Deeps: The deeps with the maximum depth found on the ocean floor are called the Oceanic Deeps.

Pacific Ocean is the largest ocean of the world which covers about 1/3rd part of the earth. In the triangular shape, it is 18000 km. wide from east to west, and 16740 km. long from north to south. Different types of land forms are found in this ocean, like: volcanic mountain ranges, earthquake affected areas and group of islands are found on its coast. More than 20000 islands found in the Pacific Ocean are classified into three parts: Melanesia, Micronesia and Polynesia. Many*troughs, long ridges, plateaus, scarps are found in the Pacific Ocean.

About 20000 islands found in the Pacific Ocean are classified into three parts: Melanesia, Micronesia and Polynesia.

The Mariana Trench is in the Pacific Ocean. It is the deepest trench of the world.

(c) Lake Van

(a) from sun

(a) Pacific Ocean

In ocean water, the sun – rays provide heat by entering down to 25 meters depth. After this depth, the effect of sun’s radiation becomes negligible. Thus, due to insolation, the surface water of ocean becomes hotter. In polar regions, the cold water being heavy settles down at the bottom. Due to being light, the warm water of the equatorial regions flows towards the polar regions by surface currents. In this way, the transmission of the temperature of oceanic water takes place.

The deeps with the maximum depth found on the ocean floor are called the Oceanic Deeps.

The oceanic bottom means the expanse of land surface under water in the oceans, that is the expansion of the heights and depths on the sea level.

There is no definite trend in the distribution of salinity along the depth. However. 

some trends emerge from the distribution of salinity in the vertical plane:

1. In the polar region, salinity is low on the surface and it increases towards the depth. Salinity remains low on the surface due to the supply of clean melt water from glaciers.

2. In the mid latitudes, salinity increases till the depth of 400 meters. After this, the amount of salinity reduces along with the depth. It happens due to more evaporation and low availability of clean water on the surface.

3. In the equatorial region, salinity is low on the surface, it increases till the depth of one thousand meters, and after that, it again starts reducing.

Mediterranean Sea, North Sea, Baltic Sea, Caribbean Sea, Black Sea, Gulf of Mexico, Biscay Bay, etc. are included in the seas and gulf of the Atlantic Ocean.

The salinity is found to be low on the surface of polar region due to the availability of clean water by the melting snow.

Internal Sea and lake are completely surrounded by the land. The amount of salinity in the Dead Sea is found to be 238 per thousand due to the factors like the high temperature, excessive warm and dry winds, more evaporation and lack of rainfall etc. The amount of salinity in the southern part of the Caspian Sea is 170 per thousand. In the northern part, it is only 14 per thousand. In the northern part of the Caspian Sea, the Ural and Volga Rivers provide the availability of the clean water. The highest salinity in the world is found in the Van Lake of Turkey which is 330 per thousand.

The quality of water is deteriorating due to water pollution. 

The following factors affect water pollution—

Domestic sewage, industrial wastes, agricultural activities, thermal pollution and marine pollution.

The earth is the only planet of the solar system which contains water in abundance. Hence it is called a ‘watery planet’. Three fourth of the earth’s total surface is covered with water.

Distribution of water: Oceans contain about 97 percent of the total water available on the earth’s surface. The remaining three percent is the fresh water found in the form of snow and ice on the ground and in lakes and rivers.

The currents of north Altantic sea start from the equator and go towards the north. These move forward along with American Coast and when these came back along the European Coast these mix with equatorial current and complete there clockwise circle. The part of north Atlantic sea which comes inside the circle is called Sargaso sea.

Oceans are useful to us in the following ways:

• They modify land temperature.
• Oceans are the source of water vapour which forms clouds. These clouds cause rainfall on the earth.
• Oceans are a major source of food for the mankind.
• They are an .excellent means of transport for bulk cargo.

The currents affect the climate of the country deeply. In winters, there are cold conditions in north west of Britain. But, the north Atlantic sea current takes easternly direction under the impact of western winds. This warm current reaches Norway and Sweden cold countries through the north-west of Britain. Because of the impact of warm currents the western ports of Britain remain open. But, in the absence of such a climate the eastern ports of North America remain frozen and closed.

The gulf-stream starts from Mexico gulf and reaches the Newfoundland Islands.

2.5% of total water is fresh water.

Tsunamis are high tidal waves (30 metres high) caused by earthquakes in oceans. On 26th December, 2004; an earthquake occurred in Indian ocean. Its focus was near Indonesia. It caused Tsunamis in Indian ocean. These waves destroyed property worth millions of rupees. About 2 lakh persons died in Indonesia, Thailand, India and Sri Lanka. In India, most affected areas were Andaman Nicobar islands, Tamil Nadu coast, and eastern coast.

Kandla is a tidal port in India.

At the time of high tide the sea water is on the rise. It happens only on full moon night and without moon night. Because on these two days the sun, moon and earth are in a straight line. On this day, the sun and moon together attract the sea water upwards. Because of this double attraction the tides rise high and it is known as high tide condition.

The Gulf-stream is the most important warm current of the world. Its width is 400 km approximately. The speed of its water is 5 km/hr. Near Newfoundland it meets labrador cold streams. As a result, there is dense fog condition. Here, the fish are also found in excess quantities. After this, it moves towards Europe. Because of its impact the winter in North-West Europe is not so cold.

The periodical vertical rise and fall of the surface of the sea water is called a tide. The rising of water is called the high tide or up tide while the falling of water is known as low tide or down tide.

Tides are caused by the gravitational pull of the moon and to some extent, the sun. Tides are useful to us as they help in navigation and fishing. At the high tide, the depth of the seas particularly gulfs, and bays increases. This enables the big ships to enter or leave the harbours easily. Due to high tides in the Hooghly river the depth of the water increases. As a result big ships enter and leave the Kolkata port which is situated on the bank of this river. Some ports such as Kandla in Gujarat and Diamond Harbour in West Bengal depend on the tides. Tides, at some places, take away the mud brought down by rivers and prevent silting of harbours. Thus tides make the rivers suitable for navigation.

Tide is very useful for ships: 

1. Because of tides the mud and the soil continue to flow out of the river mouth. As a result, there is no deposits of soil on such coastal ports and ships can come in the interior.

2. Big and heavy ships wait for tides in the deep sea. When there is high tide the ships along with the high tides reach the ports. Once they unload the cargo, they again wait for the tides. So, that they can go back easily to the sea. The ports of Kolkata and London are such examples.

On 26th Dec, 2004 there were most dangerous Tsunami tides in Indian Ocean. These were created by an earthquake which came on the sea surface measuring 9 points on Richter scale. The epicentre of this earthquake was the western course of Indonesia. In a matter of a few hours these waves brought heavy destruction in 11 countries bordering Indian Ocean. There was a great loss of life and property and the effect was experienced from Africa to Thailand.

According to an estimated figure, there was a loss Of life and property worth Rs. 5322 crore in India. The worst affected were Tamil Nadu, Kerela, Andhra Pradesh and Pondicherry. More than 2 lakh people were killed and many more were injured.