Climatology & Oceanography PDF

# Climatology & Oceanography ## Marginal Seas - The South Atlantic Ocean is characterized by the absence of marginal seas. - On the contrary, the European and the American side of the North Atlantic have a number of broad and extensive marginal seas. - The marginal seas of the European side compr...

# Climatology & Oceanography ## Marginal Seas - The South Atlantic Ocean is characterized by the absence of marginal seas. - On the contrary, the European and the American side of the North Atlantic have a number of broad and extensive marginal seas. - The marginal seas of the European side comprise the Baltic Sea, the North Sea, and the Mediterranean Sea. ### Mediterranean Sea - Extends from east to west, and has a very irregular coastline dividing it into sub-seas. - Bounded by Europe and Asia Minor on the north, and Africa to the south. - Surrounded by land except for a narrow connection with the Atlantic Ocean through the Straight of Gibraltar. - Connected with the Black Sea through the Bosporus Strait which is very narrow. - The Suez Canal, which is man-made, connects it with the Red Sea. - Atlantic Ocean water flows into the Mediterranean through the Straight of Gibraltar as a surface flow. - Because of the high evaporation of the water that comes in, the salinity of the Mediterranean water is increased considerable, causing the sinking of water which returns to the open ocean through the Strait of Gibraltar. ## Bottom Relief of the Oceans - The Caribbean Sea and the Gulf of Mexico together form the "American Mediterranean". - The Caribbean Sea is separated from the open ocean by the islands of Cuba, Hispaniola, Puerto Rico and Jamaica, which form the northern boundary of this sea. - The Greater Antilles extends from the Virgin Islands to the continental shelf of South America near the Island of Trinidad. - The Caribbean Sea is divided into four basins namely, Venezuela, Colombia, Cayman and Yucatan Basins. - The depth of all these basins exceeds 4000 meters. ### Gulf of Mexico - Simple structure with broad continental shelf all around its margin. - The maximum depth of this broad basin exceeds 3600 meters. - Connected with the Caribbean Sea by the Yucatan Strait. - Connected with the Atlantic Ocean only through the Strait of Florida. - The strait is nearly 1000 meters deep. ## The Pacific Ocean - Shape and Size: Triangular in shape with its apex in the Bering Strait. - Bounded by Asia and Australia on the west, and North America and South America to the east. - Antarctica lies to the south of this vast ocean. - Length from north to south is 14,900 km. - Width along the equator is a little more than 16,000 km. ### Bottom Relief - The continental shelf surrounding the margin of the Pacific Ocean is controlled by the shape and structure of its coastline. - The width of the shelf on the eastern margin of this ocean is rather narrow, because of the presence of the Rockies and the Andes Mountains parallel to the west coasts of North and South Americas. - This means that the continental shelves have become very narrow, with a width of only 80 km. - On the western margin of this ocean, due to the absence of mountain chains or plateaus, the continental shelf is broad. - The continental shelves adjoining the coasts of Australia, East Indies and East Asia are relatively much more broader. - The average depth hardly exceeding 1000 meters. ### Ridges and Basins - The major part of the Pacific Ocean floor is made up of the abyssal plains. - Deeper than those in other oceans. - The major characteristic of the deep-sea plains is that they are deeper than those in other oceans. - They are deeper than those in other oceans. - Beyond the continental slopes there is a sudden increase in the depth of the deep-sea plains. - The bottom relief is characterized by the absence of any mid-oceanic ridges. - There are a few submarine ridges of medium heights, and extensive and curvilinear submarine plateaus on the ocean floor. ### Islands of the Pacific Ocean - Islands in the Pacific Ocean is about 20,000 but their total area is relatively less. - Most big islands of the Western Pacific are structurally parts of the mainland that have been submerged under seawater. - Between the mainland and these islands there are submerged basins. - The Kurile Islands, the Japan Islands, Philippines, East Indies and New Zealand are the most important. - Islands off the coast of British Columbia, and the Chilean Islands are important. - They represent folded mountain chains with numerous volcanic peaks. - They are located in weak crustal zones, so they are subjected to frequent earthquakes. - There are several smaller scattered groups of islands in the south-western part of the Pacific Ocean. - They are classified under three names on the basis of their racial groupings: Melanesia, Micronesia, and Polynesia. - Melanesia includes the islands of Solomons, New Hebrides and Fiji. - All the islands of the Melanesia group are situated to the south of Micronesia group of islands. - Most of these are coral islands. - New Guinea Island is also included in this group. - The Micronesia group includes Carolines, Marshalls, Gilbert and Ellice Islands. - Most of these islands are small-sized and are situated north of the equator to the west of 180° longitude. - Almost all of these are coral islands. - The Polynesia group of islands are situated in a triangular area. - Bounded in the north by Hawaii Islands, in the south-east by Easter Island and in the south-west by New Zealand. - Line Islands, Samoa, Tonga, Cook, Society and Tuamotu Islands are some of the important ones that form this group. - The northernmost island of the Pacific islands is Hawaii Islands. - It is connected with the Hawaii Submarine Ridge. ## The Indian Ocean - Shape and Size: Second to the Atlantic Ocean in respect of area. - Covers 20% of the total area of all the oceans of the world. - It is bounded by the Indian Union, Pakistan and Iran in the north; by Australia, Sunda Island and Malaysia in the east; by the Arabian Peninsula and Africa in the west; and by the Atlantic Ocean to the south of the southern tip of Africa in the south-west. ### Bottom Relief - The continental shel surrounding this ocean varies in its width. - The average width is about 96 km. - It varies from 192 km to 208 km. - The depth of water lies between 50 and 200 meters. - The depth of the sea on the seaward edge of the shelf along the west coast of Australia has been measured from 300 m to 400 m. - The shelf is 960 km wide between Australia and New Guinea Island. - Due to intense glaciation, the structure of the shelf adjoining the Antarctica has become very complex. - The landward margins of the shelf are 150-200 m deep. - The seaward margins register depth varying from 400 to 500 meters. - In the tropical areas different types of coral reefs such as, fringing reef, barrier reef and atoll are found on the shelf. - The continental slopes on the outer margins of the shelf are marked by the extreme steepness, angle of slope varying from 10° to 30°. ### Ridges and Basins - The bottom relief of the Indian Ocean resembles that of the Atlantic Ocean. - It has a continuous central ridge, called the Arabic-Indian Ridge, together with its southern extension, the Kerguelen-Gaussberg Ridge, which connects with the Antarctic continent. - The central ridge separates the eastern basin from the western basin. - The oceanic islands in this ocean are situated on the central ridge and on its cross ridges. - Examples are the Cocos and Christmas Islands. - The Indian Ocean is characterized by having a large number of broad submarine ridges, separating several individual basins of the abyssal plain. - One of its most distinguishing features is the presence of the series of curving ridges in the north-west segment of the ocean. ### Islands - Islands in the Indian Ocean are far less, than those in the Pacific or Atlantic Oceans. - Some of the islands are supposed to be parts of the mainland. - Madagaskar andr Sri Lanka are the most prominent. - Socotra, Zanzibar and Comoro are other islands. - Even Seychelles Island is taken to be a part of the mainland. - The Andaman and Nicobar Islands are on the outer ridges of the Arakan Yoma Mountains. - The Laccadives and Maldives are coral islands situated in the Arabian Sea off south - western India. - Smaller groups of islands are on the central ridge farther south. - The Kerguelen is situated on the St. Paul Plateau. - Mauritius and Reunion are volcanic cones with steep slopes. - There is a dearth of islands in the eastern part of the Indian Ocean due to the fact that the ocean bottom is uniformly deep. - Examples: Cocos and the Christmas Islands. ## The Arctic Ocean - Shape and Size: Almost circular in shape and surrounds the North Pole of the earth. - Total area is about 14 million km2. - It surrounds the North Pole of the earth. - Surrounded on all sides by land masses except at a few places where it is connected with the Atlantic and the Pacific oceans. - Connected with the Pacific Ocean through the Bering Strait. - The waters of the Arctic Basin mix with those of the Atlantic Ocean through the open seas between Greenland, Iceland and British Islands. ### Bottom Relief - The continental shelf to the north of Alaska and Greenland is 96-192 km wide. - The shelf is much wider along the north coast of Eurasia. - Variations range from 480 km to 1960 km. - There are several submarine valleys on the continental shelf. - The Santa Anna shelf is the biggest depression. - The continental shelf in the eastern and northern part of the ocean basin is relatively wider varying from 160 to 640 km in width. - The Canadian Archipelago, Greenland and several island groups of Eurasia rise on the Arctic continental shelves. ### Ridges and Basins - The most important ridge is the central Lomonosov Ridge. - The depth of water over the higher elevations of the ridge ranges from 517-900 fathoms. - The Trans-Arctic extension of the Mid-Atlantic Ridge, which is known as the Nansen; separates the Eurasian Basin into two parts. - The geographic North Pole has been located in the Fram Basin. - The Fram Basin is 2345 fathoms deep. It is surrounded by the Nansen and Lomonosov Ridges. - The Nansen Basin (2300 fathoms) is situated in the middle of the Nansen Cordillera and the coast of Eurasia. - The Alpha Cordillera divides the Amerasia Basin into two sub-basins. - The Makarob Basin is 2200 fathoms deep. - The Canada Basin is the biggest one. - It lies between the Beaufort shelf and the Alpha Ridge. - The average depth of this basin is 2091 fathoms. ### Islands - The rim of the Arctic Basin is dotted with a large number of islands. - Some of the large and extensive islands like the Canadian Archipelago, the New Siberian Islands, and Novaya Zemlya are in fact parts of the submerged margins of the land-masses with broad continental shelves. - Other islands are Spitzbergen, Bear Island and Jan Mayen, which represent the higher parts of the submarine ridges. ### Marginal Seas - The Arctic Ocean is characterized by a large number of marginal seas. - They lie on the northern coasts of the land masses. - Examples include the Beaufort Sea off the coast of Alaska; the East Siberian Sea and Laptev Sea along the Siberian coast; the Kara Sea between the mouth of the river Ob draining into the Arctic Basin and the Island of Novaya Zemlya; and the Barents Sea situated between Spitzbergen and Norway.