The natural environment encompasses all living and non-living things occurring naturally on Earth or some region thereof. It is an environment that encompasses the interaction of all living species.[1] The concept of the natural environment can be distinguished by components:
- Complete ecological units that function as natural systems without massivehuman intervention, including all vegetation, microorganisms, soil, rocks,atmosphere and natural phenomena that occur within their boundaries.
- Universal natural resources and physical phenomena that lack clear-cut boundaries, such as air, water, and climate, as well as energy, radiation,electric charge, and magnetism, not originating from human activity.
The natural environment is contrasted with the built environment, which comprises the areas and components that are strongly influenced by humans. A geographical area is regarded as a natural environment.Water on Earth
An ocean is a major body of saline water, and a component of the hydrosphere. Approximately 71% of the Earth's surface (an area of some 362 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the World Ocean or global ocean.
[7][8] This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance tooceanography.
[9] The major oc
eanic divisions are defined in part by the continents, variousarchipelagos, and other criteria: these divisions are (in descending order of size) thePacific Ocean, the Atlantic Ocean, the Indian Ocean, the Southern Ocean and the Arctic Ocean.
[edit]Rivers A river is a naturalwatercourse,[10] usuallyfreshwater, flowing toward anocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be termed by several other names, including stream, creek and brook. In the United States a river is generally classified as a watercourse more than 60 feet (18 metres) wide. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of thehydrological cycle. Water within a river is generally collected from precipitationthrough surface runoff, groundwater recharge, springs, and the release of water stored in glaciers and snowpacks.A river is a naturalwatercourse,[10] usuallyfreshwater, flowing toward anocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be termed by several other names, including stream, creek and brook. In the United States a river is generally classified as a watercourse more than 60 feet (18 metres) wide. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of thehydrological cycle. Water within a river is generally collected from precipitationthrough surface runoff, groundwater recharge, springs, and the release of water stored in glaciers and snowpacks.A river is a naturalwatercourse,[10] usuallyfreshwater, flowing toward anocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be termed by several other names, including stream, creek and brook. In the United States a river is generally classified as a watercourse more than 60 feet (18 metres) wide. The water in a river is usually in a channel, made up of a stream bed between banks. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Flood plains may be very wide in relation to the size of the river channel. Rivers are a part of thehydrological cycle. Water within a river is generally collected from precipitationthrough surface runoff, groundwater recharge, springs, and the release of water stored in glaciers and snowpacks.
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