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  2. Ionosphere - Wikipedia

    en.wikipedia.org/wiki/Ionosphere

    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 ...

  3. F region - Wikipedia

    en.wikipedia.org/wiki/F_region

    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 ...

  4. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    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 ...

  5. Upper atmosphere - Wikipedia

    en.wikipedia.org/wiki/Upper_atmosphere

    The mesosphere, which on Earth lies between the altitudes of about 50 and 80 kilometres (31 and 50 mi), sometimes considered part of the "middle atmosphere" rather than the upper atmosphere; The thermosphere, which on Earth lies between the altitudes of about 80 and 700 kilometres (50 and 435 mi)

  6. Protonosphere - Wikipedia

    en.wikipedia.org/wiki/Protonosphere

    The protonosphere is a layer of the Earth's atmosphere (or any planet with a similar atmosphere) where the dominant components are atomic hydrogen and ionic hydrogen . [1] It is the outer part of the ionosphere , and extends to the interplanetary medium .

  7. Thermosphere - Wikipedia

    en.wikipedia.org/wiki/Thermosphere

    A contraction of the thermosphere has been observed as a possible result in part due to increased carbon dioxide concentrations, the strongest cooling and contraction occurring in that layer during solar minimum. The most recent contraction in 2008–2009 was the largest such since at least 1967. [14] [15] [16]

  8. Ionospheric pierce point - Wikipedia

    en.wikipedia.org/wiki/Ionospheric_pierce_point

    Here R is the mean Earth radius, H is the mean height of the ionosphere shell. The IPP or Ionospheric Pierce Point is the altitude in the ionosphere where electron density is greatest. [1] These points can change based on factors like time of day, solar activity, and geographical location, which all influence ionospheric conditions. [2]

  9. Heart - Wikipedia

    en.wikipedia.org/wiki/Heart

    The heart wall is made up of three layers: the inner endocardium, middle myocardium and outer epicardium. These are surrounded by a double-membraned sac called the pericardium. The innermost layer of the heart is called the endocardium. It is made up of a lining of simple squamous epithelium and covers heart chambers