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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 oceanic crust displays a pattern of magnetic lines, parallel to the ocean ridges, frozen in the basalt. A symmetrical pattern of positive and negative magnetic lines emanates from the mid-ocean ridge. [24] New rock is formed by magma at the mid-ocean ridges, and the ocean floor spreads out from this point.
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of the ocean is very deep, where the seabed is known as the abyssal plain. Seafloor spreading creates ...
In geology, sima (/ ˈ s aɪ m ə /) is an antiquated [1] blended term for the lower layer of Earth's crust. This layer is made of rocks rich in magnesium silicate minerals. Typically, when the sima comes to the surface, it is basalt, so sometimes this layer is called the 'ocean layer' of the crust. The sima layer is also called the 'basal ...
The upper part of the heterosphere is composed almost completely of hydrogen, the lightest element. [29] The planetary boundary layer is the part of the troposphere that is closest to Earth's surface and is directly affected by it, mainly through turbulent diffusion. During the day the planetary boundary layer usually is well-mixed, whereas at ...
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] The thicker crust is the continental crust , which is less dense [ 11 ] and is felsic -rich (igneous rocks rich in elements that form feldspar and quartz ). [ 12 ]
Long before cables had been laid on the oceans’ floors, cross-continent communication relied on shortwave radio waves reflecting against the ionosphere—the atmospheric layer capable of ...
The F 2 layer exists from about 220 to 800 km (140 to 500 miles) above the surface of the Earth. The F 2 layer is the principal reflecting layer for HF radio communications during both day and night. The horizon-limited distance for one-hop F 2 propagation is usually around 4,000 km (2,500 miles). The F 2 layer has about 10 6 e/cm 3. However ...