The F region of the ionosphere is home to the F layer of ionization, also called the Appleton layer , after the English physicist Edward Appleton. The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation Sir Edward Victor Appleton, GBE ( September 6, 1892 – April 21, 1965) was an English Physicist. As with other ionospheric sectors, 'layer' implies a concentration of plasma, while 'region' is the area that contains the said layer. The F region contains ionized gases at a height of around 150–800 km above sea level, placing it in the Earth’s thermosphere, a hot region in the upper atmosphere, and also in the heterosphere, where chemical composition varies with height. Mean sea level (MSL is the average (mean height of the Sea, with reference to a suitable reference surface The thermosphere is the layer of the Earth's atmosphere directly above the Mesosphere and directly below the Exosphere. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Generally speaking, the F region has the highest concentration of free electrons and ions anywhere in the atmosphere. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge It may be thought of as comprising two layers, the F1-and F2-layers.
The F-region is located directly above the E region (formerly the Kennelly-Heaviside layer) and below the protonosphere. The Kennelly-Heaviside layer, also known as the E region or simply the Heaviside layer, is a layer of ionised Gas occurring at 90&ndash150 km The ionosphere is the uppermost part of the atmosphere, distinguished because it is Ionized by solar radiation It acts as a dependable reflector of radio signals as it is not affected by atmospheric conditions, although its ionic composition varies with the sunspot cycle. It reflects normal-incident frequencies at or below the critical frequency (approximately 10 MHz) and partially absorbs waves of higher frequency.
The F region is the region of the ionosphere which is very important for HF radio wave propagation. This F region is very anomalous in nature.
F1 and F2 Layers
The F1 layer is the lower sector of the F layer and exists from about 150 to 220 km above the surface of the Earth and only during daylight hours. It is composed of a mixture of molecular ions O2+ and NO+, and atomic ions O+. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Above the F1 region, atomic oxygen becomes the dominant constituent because lighter particles tend to occupy higher altitudes above the turbopause (at ~100 km). The turbopause marks the altitude in the Earth's atmosphere below which turbulent mixing dominates This atomic oxygen provides the O+ atomic ions that make up the F2 layer. The F1 layer has approximately 5 × 105 e/cm3 (free electrons per cubic centimeter) at noontime and minimum sunspot activity, and increases to roughly 2 × 106 e/cm3 during maximum sunspot activity. A sunspot is a region on the Sun 's surface ( Photosphere) that is marked by intense magnetic activity which inhibits Convection, forming The density falls off to below 104 e/cm3 at night.
- The F1 layer merges into the F2 layer at night.
- Though fairly regular in its characteristics, it is not observable everywhere or on all days. The principal reflecting layer during the summer for paths of 2,000 to 3,500 km is the F1 layer.
- The F2 layer exists from about 220 to 800 km above the surface of the Earth. The F2 layer is the principal reflecting layer for HF communications during both day and night. The horizon-limited distance for one-hop F2 propagation is usually around 4,000 km. In Telecommunication, the term hop has the following meanings The excursion of a Radio wave from the Earth to the Ionosphere Radio propagation is a term used to explain how Radio waves behave when they are Transmitted, or are propagated from one point on the Earth The F2 layer has about 106 e/cm3. However, variations are usually large, irregular, and particularly pronounced during magnetic storms. The F layer behaviour is dominated by the complex thermospheric winds.
References
This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain. Federal Standard 1037C, entitled Telecommunications Glossary of Telecommunication Terms is a United States Federal Standard issued by the General Services Administration The Encyclopædia Britannica Eleventh Edition (1910–1911 is a 29-volume reference work that marked the beginning of the Encyclopædia Britannica The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic