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Relationship of the atmosphere and ionosphere. The ionosphere (/ aɪ ˈ ɒ n ə ˌ s f ɪər /) [1] [2] is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level, [3] a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar ...
The ocean is the body of salt water that covers approximately 70.8% of Earth. [8] In English, the term ocean also refers to any of the large bodies of water into which the world ocean is conventionally divided. [9] The following names describe five different areas of the ocean: Pacific, Atlantic, Indian, Antarctic/Southern, and Arctic.
The oceanic zone is typically defined as the area of the ocean lying beyond the continental shelf (e.g. the neritic zone), but operationally is often referred to as beginning where the water depths drop to below 200 metres (660 ft), seaward from the coast into the open ocean with its pelagic zone.
Most of Earth's surface is ocean water: 70.8% or 361 million km 2 (139 million sq mi). [96] This vast pool of salty water is often called the world ocean, [97] [98] and makes Earth with its dynamic hydrosphere a water world [99] [100] or ocean world. [101] [102] Indeed, in Earth's early history the ocean may have covered Earth completely. [103]
Total atmospheric mass is 5.1480×10 18 kg (1.135×10 19 lb), [42] about 2.5% less than would be inferred from the average sea level pressure and Earth's area of 51007.2 megahectares, this portion being displaced by Earth's mountainous terrain. Atmospheric pressure is the total weight of the air above unit area at the point where the pressure ...
Geologically, an ocean is an area of oceanic crust covered by water. Oceanic crust is the thin layer of solidified volcanic basalt that covers the Earth's mantle. Continental crust is thicker but less dense. From this perspective, the Earth has three oceans: the World Ocean, the Caspian Sea, [citation needed] and the Black Sea.
Ocean – the four to seven largest named bodies of water in the World Ocean, all of which have "Ocean" in the name (see: Borders of the oceans for details). Sea has several definitions: [a] A division of an ocean, delineated by landforms, [6] currents (e.g., Sargasso Sea), or specific latitude or longitude boundaries. This includes but is not ...
Antarctica provides the water hemisphere with the majority of Earth's ice. Most of the Pacific Ocean and the Indian Ocean, and the whole Southern Ocean, are in the water hemisphere. The water hemisphere is approximately 89 percent water (almost all pertaining to the World Ocean), 6 percent dry land and 5 percent polar ice cap. [1]