The Atlantic Ocean is the second-largest ocean. It covers approximately one-fifth of the Earth’s surface and is second only to the Pacific Ocean in size. It separates the continents of Europe and Africa to the east from those of North and South America to the west. The ocean’s name is derived from the Greek god Atlas and means the “Sea of Atlas.”
The Atlantic Ocean appears as an elongated, S-shaped basin extending in a north-south direction. It is bounded by North and South America on the west and Europe and Africa on the east. The Atlantic Ocean is linked to the Pacific Ocean by the Arctic Ocean on the north and the Drake Passage on the south. It is divided into the North Atlantic and South Atlantic by Equatorial Counter-Currents at about 8° North latitude. Panama Canal provides a man-made connection between the Atlantic and Pacific Oceans. On the east, the dividing line between the Atlantic and the Indian Ocean is the 20° East meridian, running south from Cape Agulhas to Antarctica. The Atlantic Ocean connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, and the Barents Sea.
With its adjacent seas, it occupies an area of about 106,460,000 km2 or 23.5% of the global ocean and has a volume of 310,410,900 km3 or 23.3% of the total volume of the earth's oceans. Excluding its marginal seas, the Atlantic Ocean covers 81,760,000 km2 and has a volume of 305,811,900 km3. The North Atlantic covers 41,490,000 km2 and the South Atlantic covers 40,270,000 km2. The average depth is 3,646m and the maximum depth, the Milwaukee Deep in the Puerto Rico Trench is 8376m. The width of the Atlantic varies from 2848 km between Brazil and Liberia to about 4830 km between the United States and Northern Africa.
The waters of the ocean move in patterns called currents. Due to the Coriolis effect, water in the North Atlantic circulates in a clockwise direction, whereas water in the South Atlantic circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal, that means, two high tides occur every 24 lunar hours. The tides are a general wave that moves from south to north. In latitudes above 40° North, some east-west oscillation occurs.
The bottom of the Atlantic Ocean has a submarine mountain range called the Mid-Atlantic Ridge (MAR), also known as a mid-ocean ridge. It is an underwater mountain system that is formed as a result of plate tectonics of a divergent plate boundary that runs from 87° N – about 333 km (207 mi) south of the North Pole – to 54 °S, just north of the coast of Antarctica. It is part of the longest mountain chain in the world, extending continuously across the ocean floors for a distance of 40,389 km from Iceland to Antarctica.
The length of the MAR is 16,000 km (approximately) and its width is 1000-1500 km. The peak of the ridge is as high as 3 km above the ocean floor, and it sometimes reaches above sea level, forming islands and island groups. These islands and island groups were created by volcanic activity.
The Mid-Atlantic Ridge separates the Atlantic Ocean into two large troughs with depths averaging between 3700 and 5500 meters (12000 and 18000 ft). Transverse ridges running between the continents and the MAR divide the ocean floor into numerous basins. Some of the larger basins are the Guiana, North American, Cape Verde, and Canaries basins in the North Atlantic. The largest South Atlantic basins are Angola, Cape, Argentina, and Brazil basins.
It was thought that the deep ocean floor is flat, but there are numerous seamounts, some guyots, and several trenches on the ocean floor. Seamounts are submarine mountains; guyots are the undersea mountain with a flat top; and trenches are long, narrow ditches. There are three trenches:
Undersea volcanoes have formed some of the Atlantic islands. For example, the Cabo Verde Islands near Africa, Bermuda near North America. Iceland is a volcanic island that rises from the Mid-Atlantic Ridge. Other Atlantic islands are parts of the same land s nearby continents. For example, the island of Great Britain near Europe, and the Falkland Islands near South America.
The Atlantic Ocean Off Azores Give Birth to Volcano
Salinity is the amount of dissolved salt in the water. The Atlantic Ocean is the saltiest ocean of all the world's major oceans. Its surface waters have higher salinity than those of any other ocean. In the open ocean, the salinity of the surface waters ranges from 33-37 parts per thousand and varies with latitude and season. Evaporation, precipitation, river inflow, and melting of sea ice influence surface salinity.
The surface water temperature range from less than −2 ° C to 29 °C (28 ° F to 84 °F). North of the equator has maximum temperatures, and polar regions have minimum values. Maximum temperature variations occur in the middle latitudes and the values vary by 7 °C to 8 °C (13°F to 14°F). The temperature of surface water varies with latitude, current systems, and season. It reflects the latitudinal distribution of solar energy.
There are four major water masses in the Atlantic Ocean.
Within the North Atlantic Ocean, ocean currents isolate a large elongated body of water known as the Sargasso Sea. It is the only sea without a land boundary. While all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents.
It is named for a genus of free-floating seaweed called Sargassum. While there are many different types of algae found floating in the ocean all around the world, the Sargasso Sea is unique in that it posses species of sargassum that are 'holopelagi' - this means that the algae not only freely float around the ocean, but it reproduces vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean. Sargassum provides a home to an amazing variety of marine species like the European eel.
The temperatures of the surface waters and water currents as well as the winds blowing across the waters influence the climate of the Atlantic Ocean and adjacent land areas. The ocean retains heat, therefore maritime climates are moderate and lack extreme seasonal variations.
Climatic zones vary with latitude.
Ocean currents transport warm and cold waters to other regions. Thus, contributing to climatic control. When winds blow over these currents, they are warmed or cooled. These winds transport moisture and warm/cool air over adjacent land areas. For example, the Gulf Stream warms the atmosphere of the British Isles and northwestern Europe, and the cold water currents contribute to heavy fog off the coast of northeastern Canada and the northwestern coast of Africa.
Hurricanes develop in the southern part of the North Atlantic Ocean. They usually hit coastal areas in the Caribbean Sea and southeastern North America.
The Atlantic Ocean has significantly contributed to the development and economy of the countries around it. It serves as a major transatlantic transportation and communication route. There are abundant deposits of oil, natural gas, and coal. The Atlantic produces much of the world’s fish.
Humans have heavily polluted some areas of the Atlantic Ocean. This pollution includes sewage from cities, waste from factories, and fertilizers and pesticides from farms. Oil spills from ships or offshore oil wells are sources of pollution, too. Overfishing is another important environmental issue in the Atlantic. Some countries have set limits on how many fish can be caught in certain areas. They have also set up programs to protect the fish that are left and to rebuild the fish populations.
