The oceans cover at around 71 percent of the earth’s surface. In fact, the oceans constitute about 97 percent of the world’s water resources. It is very deep and large sea which has saline water is called an ocean. The remaining 3 percent of the world’s water is in the form of ice in the polar regions of the earth. The total volume of ocean is about 1.35 billion cubic kilometers with an average depth of around 3,700 meters. There are 230, 000 known species and may around 2 million species in ocean.
The average depth of the oceans is about 3.9 kilometers. All the oceans are interconnected by water and characterized by saline water (salty water). The pressure within the oceans varies from 1 atmosphere at the surface of sea is about 1000 atmospheres at the greatest depth.
Composition of ocean water
The water in ocean is a mixture of various salts. These salts are found in ocean such as magnesium, potassium metals, sodium, and calcium. There are two ways in which ocean get these salts which are as given below –
- The ocean also gets these salts from the rivers which flow into it.
- The ocean gets the salt from the weathering (breaking) of rocks and eroding of rocks present on land.
As the time passes, some of the dissolved salts are present in the water of ocean precipitate and settle down on the floor of the ocean as sediments.
How Oceans Regulate the Temperature of Land
There are two ways in which ocean regulate the temperature of land which are as given below –
- By convection currents that flow in deep sea due to difference in temperature
- By oceanic currents that flow in them due to rotation of earth and blowing of winds.
Let us discuss in detail. When wind blows over the surface of an ocean, it causes the water to flow from one place to another. Similarly, when the earth rotates, it also causes the sea-water to flow along a particular path. This flow of water in the ocean from one place to another is called oceanic current.
At the greater depth in the oceans, the difference in temperature between different points causes the water to flow. Due to oceanic currents and convection currents, this flow of water carries heat from lower latitudes to higher latitudes and regulates the temperature of land. Because of this regulation, the difference in temperature between any two points in the ocean is never more than 10 degree Celsius.