Matches in DBpedia 2016-04 for { <http://wikidata.dbpedia.org/resource/Q803957> ?p ?o }
Showing triples 1 to 61 of
61
with 100 triples per page.
- Q803957 subject Q6263008.
- Q803957 abstract "A Birkeland current is a set of currents that flow along geomagnetic field lines connecting the Earth’s magnetosphere to the Earth's high latitude ionosphere. In the Earth’s magnetosphere, the currents are driven by the solar wind and interplanetary magnetic field and by bulk motions of plasma through the magnetosphere (convection indirectly driven by the interplanetary environment). The strength of the Birkeland currents changes with activity in the magnetosphere (e.g. during substorms). Small scale variations in the upward current sheets (downward flowing electrons) accelerate magnetospheric electrons which, when they reach the upper atmosphere, create the Auroras Borealis and Australis. In the high latitude ionosphere (or auroral zones), the Birkeland currents close through the region of the auroral electrojet, which flows perpendicular to the local magnetic field in the ionosphere. The Birkeland currents occur in two pairs of field-aligned current sheets. One pair extends from noon through the dusk sector to the midnight sector. The other pair extends from noon through the dawn sector to the midnight sector. The sheet on the high latitude side of the auroral zone is referred to as the Region 1 current sheet and the sheet on the low latitude side is referred to as the Region 2 current sheet.The currents were predicted in 1908 by Norwegian explorer and physicist Kristian Birkeland, who undertook expeditions beyond the Arctic Circle to study the aurora. He rediscovered, using simple magnetic field measurement instruments, that when the aurora appeared the needles of magnetometers changed direction, confirming the findings of Anders Celsius and assistant Olof Hjorter more than a century before. This could only imply that currents were flowing in the atmosphere above. He theorized that somehow the Sun emitted a cathode ray, and corpuscles from what is now known as a solar wind entered the Earth’s magnetic field and created currents, thereby creating the aurora. This view was scorned by other researchers, but in 1967 a satellite, launched into the auroral region, showed that the currents posited by Birkeland existed. In honour of him and his theory these currents are named Birkeland currents. A good description of the discoveries by Birkeland is given in the book by Jago.Professor Emeritus of the Alfvén Laboratory in Sweden, Carl-Gunne Fälthammar wrote: "A reason why Birkeland currents are particularly interesting is that, in the plasma forced to carry them, they cause a number of plasma physical processes to occur (waves, instabilities, fine structure formation). These in turn lead to consequences such as acceleration of charged particles, both positive and negative, and element separation (such as preferential ejection of oxygen ions). Both of these classes of phenomena should have a general astrophysical interest far beyond that of understanding the space environment of our own Earth."".
- Q803957 thumbnail Schematic-of-combined-FACs-and-ionospheric-current-systems.png?width=300.
- Q803957 wikiPageExternalLink nph-abs_connect?db_key=ALL&bibstem=Astrophysics+and+Space+Science&year=1988&volume=144.
- Q803957 wikiPageExternalLink nph-bib_query?bibcode=1988Ap%26SS.144..155P&db_key=AST&data_type=HTML&format=&high=42ca922c9c21187.
- Q803957 wikiPageExternalLink nph-data_query?bibcode=1963IAUS...16...35A&db_key=AST&link_type=ABSTRACT&high=42ca922c9c23043.
- Q803957 wikiPageExternalLink nph-data_query?bibcode=1967SSRv....7..140A&db_key=AST&link_type=ABSTRACT&high=42ca922c9c23043.
- Q803957 wikiPageExternalLink nph-data_query?bibcode=1967SoPh....1..220A&db_key=AST&link_type=ABSTRACT&high=42ca922c9c23043.
- Q803957 wikiPageExternalLink nph-data_query?bibcode=1975SSRv...17..563C&db_key=AST&link_type=ABSTRACT&high=42ca922c9c00817.
- Q803957 wikiPageExternalLink nph-data_query?bibcode=1978Ap%26SS..58..207P&db_key=AST&link_type=ABSTRACT&high=42ca922c9c00817.
- Q803957 wikiPageExternalLink ampere.jhuapl.edu.
- Q803957 wikiPageExternalLink nph-iarticle_query?1988Ap%26SS.144...73C.
- Q803957 wikiPageExternalLink dysprosium.jhuapl.edu.
- Q803957 wikiPageExternalLink elec_currents.html.
- Q803957 wikiPageExternalLink pinch_en.html.
- Q803957 wikiPageExternalLink Physics_of_the_Plasma_Universe_%28Book%29.
- Q803957 wikiPageExternalLink 0,11855,5-10100-72-39144987-0,00.html.
- Q803957 wikiPageWikiLink Q11406.
- Q803957 wikiPageWikiLink Q11523.
- Q803957 wikiPageWikiLink Q14620.
- Q803957 wikiPageWikiLink Q1571116.
- Q803957 wikiPageWikiLink Q162219.
- Q803957 wikiPageWikiLink Q176609.
- Q803957 wikiPageWikiLink Q176916.
- Q803957 wikiPageWikiLink Q1958130.
- Q803957 wikiPageWikiLink Q210009.
- Q803957 wikiPageWikiLink Q212871.
- Q803957 wikiPageWikiLink Q2189517.
- Q803957 wikiPageWikiLink Q21994628.
- Q803957 wikiPageWikiLink Q2359410.
- Q803957 wikiPageWikiLink Q25236.
- Q803957 wikiPageWikiLink Q25272.
- Q803957 wikiPageWikiLink Q2549249.
- Q803957 wikiPageWikiLink Q3141097.
- Q803957 wikiPageWikiLink Q333921.
- Q803957 wikiPageWikiLink Q34777.
- Q803957 wikiPageWikiLink Q405372.
- Q803957 wikiPageWikiLink Q40609.
- Q803957 wikiPageWikiLink Q4445010.
- Q803957 wikiPageWikiLink Q461624.
- Q803957 wikiPageWikiLink Q5039762.
- Q803957 wikiPageWikiLink Q5358042.
- Q803957 wikiPageWikiLink Q54945.
- Q803957 wikiPageWikiLink Q552565.
- Q803957 wikiPageWikiLink Q577763.
- Q803957 wikiPageWikiLink Q5807749.
- Q803957 wikiPageWikiLink Q619254.
- Q803957 wikiPageWikiLink Q6263008.
- Q803957 wikiPageWikiLink Q6500960.
- Q803957 wikiPageWikiLink Q6634041.
- Q803957 wikiPageWikiLink Q6810954.
- Q803957 wikiPageWikiLink Q6915.
- Q803957 wikiPageWikiLink Q711256.
- Q803957 wikiPageWikiLink Q732722.
- Q803957 wikiPageWikiLink Q79833.
- Q803957 wikiPageWikiLink Q81130.
- Q803957 wikiPageWikiLink Q944644.
- Q803957 wikiPageWikiLink Q945175.
- Q803957 comment "A Birkeland current is a set of currents that flow along geomagnetic field lines connecting the Earth’s magnetosphere to the Earth's high latitude ionosphere. In the Earth’s magnetosphere, the currents are driven by the solar wind and interplanetary magnetic field and by bulk motions of plasma through the magnetosphere (convection indirectly driven by the interplanetary environment). The strength of the Birkeland currents changes with activity in the magnetosphere (e.g. during substorms).".
- Q803957 label "Birkeland current".
- Q803957 depiction Schematic-of-combined-FACs-and-ionospheric-current-systems.png.