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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 ...
F2 propagation (F2-skip) is the reflection of VHF signals off the F2 layer of the ionosphere. The phenomenon is rare compared to other forms of propagation (such as sporadic E propagation , or E-skip) but can reflect signals thousands of miles beyond their intended broadcast area, substantially farther than E-skip.
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.
Specifically, geosynchronous Earth orbit (GEO) may be a synonym for geosynchronous equatorial orbit, [2] or geostationary Earth orbit. [3] To avoid confusion, geosynchronous satellites that are not in geostationary orbit are sometimes referred to as being in an inclined geostationary orbit (IGSO) .
Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [2] and released to the public in January 2007. [3] Quizlet's primary products include digital flash cards, matching games, practice electronic assessments, and live quizzes. In 2017, 1 in 2 high school students used Quizlet. [4]
On May 6, 2023, version 0.99.9d was published, which changed it to a 9-step rating scale. [3] In this version, the wind speed damage indicator was introduced, which made it the first tornado intensity and damage scale to use measured wind speeds and Doppler weather radar measured wind speeds. [ 3 ]
ViaSat-3 is a planned global constellation of three geostationary K a-band communications satellites, the first of which was launched in 2023. [1] Operated by Viasat, Inc., the satellites are intended to provide broadband connectivity with speeds of 100-plus megabits per second to homes, business and enterprise internet users, commercial, government and business aircraft, as well as government ...
The International Geography Olympiad (iGeo) is an annual competition for 16- to 19-year-old geography students from all over the world. Students chosen to represent their countries are some of the best, chosen from thousands of students who participate enthusiastically in their own National Geography Olympiads. iGeo tests the abilities of every ...