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Earth's land covers 29.2%, or 149 million km 2 (58 million sq mi) of Earth's surface. The land surface includes many islands around the globe, but most of the land surface is taken by the four continental landmasses, which are (in descending order): Africa-Eurasia, America (landmass), Antarctica, and Australia (landmass).
From the planetary surface of the Earth, the average height of the troposphere is 18 km (11 mi; 59,000 ft) in the tropics; 17 km (11 mi; 56,000 ft) in the middle latitudes; and 6 km (3.7 mi; 20,000 ft) in the high latitudes of the polar regions in winter; thus the average height of the troposphere is 13 km (8.1 mi; 43,000 ft).
The stratosphere is the second-lowest layer of Earth's atmosphere. It lies above the troposphere and is separated from it by the tropopause. This layer extends from the top of the troposphere at roughly 12 km (7.5 mi; 39,000 ft) above Earth's surface to the stratopause at an altitude of about 50 to 55 km (31 to 34 mi; 164,000 to 180,000 ft).
Earth's crust ranges from 5 to 70 kilometres (3.1–43.5 mi) [7] in depth and is the outermost layer. [8] The thin parts are the oceanic crust , which underlies the ocean basins (5–10 km) and is mafic -rich [ 9 ] (dense iron-magnesium silicate mineral or igneous rock ). [ 10 ]
Troposphere – The lowest layer of the atmosphere; Planetary boundary layer – The lowest part of the atmosphere, directly influenced by contact with the planetary surface; By air turbulence Heterosphere – Upper parts of the atmosphere in which the component gases are not well mixed; Turbopause – The altitude in the Earth's atmosphere ...
The troposphere, stratosphere, mesosphere, thermosphere, and exosphere are the five layers which make up Earth's atmosphere. 75% of the mass in the atmosphere is located within the troposphere, the lowest layer. In all, the atmosphere is made up of about 78.0% nitrogen, 20.9% oxygen, and 0.92% argon, and small amounts of other gases including ...
Land is often defined as the solid, dry surface of Earth. [1] The word land may also collectively refer the collective natural resources of Earth, [2] including its land cover, rivers, shallow lakes, its biosphere, the lowest layer of the atmosphere (troposphere), groundwater reserves, and the physical results of human activity on land, such as architecture and agriculture. [3]
The troposphere is the lowest layer of the atmosphere. This extends from the planetary surface to the bottom of the stratosphere. The troposphere contains 75–80% of the mass of the atmosphere, [9] and is the atmospheric layer wherein the weather occurs; the height of the troposphere varies between 17 km at the equator and 7.0 km at the poles.