Most of our planet's surface is covered with water. 71% of the Earth's land area is covered by the ocean, while only 29% is covered by land. But what do we know about the oceans today? Read the most interesting facts about the oceans in this post.
How many oceans are there?
Four or five. This may seem strange, but it all depends on the point of view. Since all oceans are connected, the boundaries between them are conditional. Traditionally, all scientists have distinguished at least four oceans - Pacific, Atlantic, Indian and Arctic. But some scientists believe that there is a sense to single out the fifth ocean - the Southern ocean, which washes Antarctica. The discussion on whether to recognize the Southern Ocean as an independent one or not has been going on for a long time - since the 17th century. And although in 2000 the international hydrographic organization recommended considering that there are five oceans on the Earth, officially the Southern Ocean is still not recognized, and its borders are not clearly defined.
Oceans of the Earth:
There are only four oceans:
Pacific Ocean, Atlantic Ocean, Indian Ocean, Arctic Ocean.
Recently, the Southern Ocean has also begun to stand out.https://cdn.pixabay.com/photo/2016/11/07/05/15/africa-1804896_960_720.jpg
Oceans in numbers
The world's oceans cover an area of 361 million square kilometers. - The area of the world's largest country is 21 times larger than that of Russia. The largest ocean is the Pacific Ocean (178.7 million sq km), followed by the Atlantic Ocean (91.6 million), the Indian Ocean (76.2 million) and the Arctic Ocean (14.7 million).
The volume of water in the world ocean is about 1.3 billion cubic km.
The average depth of the ocean is about 3.7 km and the maximum depth is about 11 km (Mariana Trench).
The temperature and salinity of the world's oceans varies greatly from place to place. Near the equator, the water temperature on the ocean surface is 28-29°C, and when approaching the poles, it drops to 0-1°C. At great depths, water temperature changes little, already at a depth of 1.5-2 km and below it is usually about 2 ° C. The average salinity of the world ocean water is about 3.5% (i.e. 1 liter of water contains about 35 grams of salt), but in places where large rivers flow into, it is much lower. For example, the water salinity in the Gulf of Finland is only 2-3 grams per liter.
And why are there oceans and continents at all?
If all water were evenly distributed over the Earth's surface, it would cover the planet in a layer of almost 3 km. However, there are large depressions on the surface of the Earth in which the oceans are located, and elevations are continents. Why?
Here's the thing. Inside our planet is liquid and consists of molten rocks. Only a small upper layer of several tens of kilometers thick is solid, and it consists of separate parts - lithospheric plates. However, the slabs are not the same - some slabs consist of granite and others of basalt. Granite has a lower density, so the granite slabs with the same mass are thicker and protrude above the basalt slabs. On thicker granite slabs, there are continents, and on basalt slabs there are oceans. And these plates constantly move, for millions of years appreciably changing the sizes and the form of continents and oceans.
Ocean currents
Water in the ocean is constantly moving, and in fact, there are constant currents - water flows constantly from one place of the world ocean to another. These currents are very powerful. For example, one of the most famous currents is the Gulf Stream, which carries up to 85 million cubic meters of water per second, and the Antarctic current, or the Western Winds, carries up to 200 million cubic meters of water per second. For comparison, the Amazon, the world's most full-flowing river, carries only 220,000 cubic meters of water per second.
Ocean currents have a huge impact on the climate in different regions of the world. For example, the warm current of the Gulf Stream increases the average temperature in Western Europe and some regions of North America by 8-10 ° C, and in winter in Norway because of the Gulf Stream at 15-20 ° C warmer than in other regions of the world at the same latitude!
Cold currents are also beneficial. For example, the cold Peruvian current flowing to the equator along the western coast of South America brings to the surface cold waters rich in oxygen and nutrients. This contributes to the rapid development of plankton, fish and other animals in this area. And the Pacific coast, along which this current flows, is the driest place on Earth, the Atacama Desert. But sometimes, on average, once every 7 years, the cold current stops and warm waters from the center of the Pacific Ocean rush to the shores of South America. This phenomenon, known as El Niño, is becoming a real disaster - the number of fish and seabirds is declining dramatically, and heavy rains are falling on the coast, causing severe flooding.
Ocean life
Life is known to have originated in the water and only appeared on land much later. The ocean is still much richer in life than the land.
1 milliliter of seawater contains tens of thousands of microorganisms. Near the surface, many small organisms, both plants, and animals are constantly floating in seawater, which is commonly known as plankton. Most of them are visible only under a microscope.
Plankton of the ocean produces about 50% of all oxygen and is the basis for the nutrition of larger marine inhabitants. Interestingly, although the total mass of plankton is not very large compared, for example, with the mass of terrestrial plants, plant plankton is almost wholly renewed in just a few days.
Thousands of species are known to make up plankton, but most of them are still not described and studied. One of the most amazing microorganisms living in the ocean is microscopic algae capable of luminescence. The ocean begins to glow at night in their habitat.The diversity of large living organisms in the ocean is also enormous. Life in the ocean is present everywhere - near the surface, in the deepest depths, in the coldest polar seas, and near hydrothermal springs with hundreds of degrees of water temperature.
There are also liquid carbon dioxide lakes at the bottom of the ocean, which do not evaporate due to the enormous pressure. Surprisingly, microorganisms live in liquid carbon dioxide!