Ce indica acul busolei atunci cand te afli la Polul Nord ?

The Canadian government has made several measurements since, which show that the North Magnetic Pole is moving continually northwestward. In 2001, an expedition located the pole at 81.3°N 110.8°W. In 2007, the latest survey found the pole at 83.95°N 120.72°W.[13] During the 20th century it moved 1100 km, and since 1970 its rate of motion has accelerated from 9 km/year to approximately 52 km/year (2001–2007 average; see also Polar drift). Members of the 2007 expedition to locate the magnetic north pole wrote that such expeditions have become logistically difficult, as the pole moves further away from inhabited locations. They expect that in the future, the magnetic pole position will be obtained from satellite data instead of ground surveys.[13]
This general movement is in addition to a daily or diurnal variation in which the North Magnetic Pole describes a rough ellipse, with a maximum deviation of 80 km from its mean position.[14] This effect is due to disturbances of the geomagnetic field by charged particles from the Sun.

omuldinluna a scris:Las si un extras dintr-un articol de wiki legat strict de polul nord magnetic.

The Canadian government has made several measurements since, which show that the North Magnetic Pole is moving continually northwestward. In 2001, an expedition located the pole at 81.3°N 110.8°W. In 2007, the latest survey found the pole at 83.95°N 120.72°W.[13] During the 20th century it moved 1100 km, and since 1970 its rate of motion has accelerated from 9 km/year to approximately 52 km/year (2001–2007 average; see also Polar drift). Members of the 2007 expedition to locate the magnetic north pole wrote that such expeditions have become logistically difficult, as the pole moves further away from inhabited locations. They expect that in the future, the magnetic pole position will be obtained from satellite data instead of ground surveys.[13]
This general movement is in addition to a daily or diurnal variation in which the North Magnetic Pole describes a rough ellipse, with a maximum deviation of 80 km from its mean position.[14] This effect is due to disturbances of the geomagnetic field by charged particles from the Sun.

Cum spuneam, e orice altceva mai putin punct fix in care sa fie orientat acul busolei in jos, cum spune teoria.

virgil a scris:La polul nord ar trebui folosita o busola in 3d, care sa permita acului sa se aseze chiar pe verticala. Acul ar putea pluti intr-un lichid care sa nu inghete (antigel), si sa fie ancorat cu o articulatie sferica intr-un vas tot sferic, care sa aiba gradatii atat in plan orizontal cat si pe un plan vertical.

meteor a scris:

virgil a scris:La polul nord ar trebui folosita o busola in 3d, care sa permita acului sa se aseze chiar pe verticala. Acul ar putea pluti intr-un lichid care sa nu inghete (antigel), si sa fie ancorat cu o articulatie sferica intr-un vas tot sferic, care sa aiba gradatii atat in plan orizontal cat si pe un plan vertical.

un fel de girscop

omuldinluna a scris:Magnetul acela genereaza un camp mult mai puternic decat cel al planetei, in imediata sa vecinatate. Totodata, acest camp nu fluctueaza in nici un fel perceptibil pentru o busola, tocmai de aceea acul sta fixat. Nu e cazul insa la oricare dintre polii magnetici ai Pamantului.

omuldinluna a scris:Ti-am raspuns deja, acul se va roti aiurea din cauza fluctuatiilor campului magnetic. Asta e chestiune verificata practic.

At the onset of the Cold War, the U.S. War Department recognized a need for a comprehensive knowledge of the North American Arctic and asked the Army to undertake the task. An assignment was made in 1946 for the newly formed Army’s Air Corps Strategic Air Command to explore the entire Arctic Ocean area. The exploration was conducted by the 46th (later re-designated the 72nd) Photo Reconnaissance Squadron and reported on as a classified Top Secret mission named Project Nanook. This project in turn was divided into a multitude of identically classified projects one of which was Project Polaris. This special project was tasked to make a radar, photographic (trimetrogon, or three-angle, cameras) and visual study of the entire Canadian Archipelago. A Canadian officer observer was assigned to accompany each flight.
Charged with directing Project Polaris was its navigation leader, 1st Lt. Frank O. Klein, a World War II combat veteran. Incidental to the project and taken up at his own initiative was a study of northern terrestrial magnetism. The study was prompted by the surprise that the fluxgate compass did not behave erratically as expected by the authorities. It oscillated no more than 1 to 2 degrees over much of the region.[10][11] With the cooperation of many of his squadron teammates in obtaining many hundreds of statistical readings, startling results were revealed. For one, the center of the north magnetic dip pole was on Prince of Wales Island some 250 miles NNW of the positions determined by Amundsen and Ross.
Also astonishing was the revelation that the dip pole occupied a larger elliptical area with foci about 250 miles apart on Boothia Peninsula and Bathurst Island. Klein called the two foci local poles for their importance to navigation in emergencies when using a “homing” procedure. Soon (about 3 months) after Klein’s findings were officially reported, a Canadian ground expedition was sent into the Archipelago to locate the position of the magnetic pole. In a letter to 1st Lt. Frank Klein dated 21 July 1948 from R. Glenn Madill, Chief of Terrestrial Magnetism, Department of Mines and Resources, Canada, he wrote, “…we can agree on one point, and that is the presence of what we can call the main magnetic pole on northwestern Prince of Wales Island. I have accepted as a purely preliminary value, the position Latitude 72 degrees N and 100 degrees Longitude West. Your value of 73 degrees 15' and 99 degrees 45’ W is in excellent agreement, and I suggest you use your value by all means." (The positions were less than 20 miles apart.)[12]

Near the North Pole the compass should always point South (ish). However, the horizontal component of the earth's magnetic field is weak so far North, and the vertical component or dip is so strong, that when the compass needle is not dipping down it aligns to any ferromagnetic material -- becoming quite useless for accurate navigation.

omuldinluna a scris:Foarte bun filmul, ia uite ce scrie la descriere:

Near the North Pole the compass should always point South (ish). However, the horizontal component of the earth's magnetic field is weak so far North, and the vertical component or dip is so strong, that when the compass needle is not dipping down it aligns to any ferromagnetic material -- becoming quite useless for accurate navigation.

adica, pe romaneste

In apropierea Polului Nord busola ar trebui sa indice mereu Sudul. Cu toate astea, componenta orizontala a campului magnetic terestru destul slaba atat de aproape de Nord, iar cea verticala atat de puternica, incat atunci cand acul busolei nu cade in jos (nota mea - cum ar fi cazul daca ai intoarce busola la verticala, cred) acesta sa aliniaza dupa orice material feromagnetic - devenind inutil pentru navigatie precisa.

Apropo de cum se comportă busola la polii magnetici ai Pămîntului, da, se comportă într-un mod deosebit: spre deosebire de orice alt punct de pe glob, la polii magnetici acul busolei are o orientare indiferentă. Cum îl pui, așa stă. Asta se întîmplă din cauză că la polii magnetici liniile de cîmp magnetic sînt exact verticale, deci acțiunea asupra unui ac magnetic orizontal este aceea de a-l înclina puțin într-un plan vertical, și nu de a-l roti în plan orizontal.

Polul magnetic este DEFINIT ca locul în care liniile de cîmp magnetic sînt verticale. Fluctuațiile sînt prea lente și prea mici pentru a fi detectate cu o busolă în cîteva minute, adică în condiții practice.

omuldinluna a scris:
De acord, sta nemiscat,

In orice caz, aceste doua comentarii ale lui AdiJapan cred ca pun punctul pe i, anume

Apropo de cum se comportă busola la polii magnetici ai Pămîntului, da, se comportă într-un mod deosebit: spre deosebire de orice alt punct de pe glob, la polii magnetici acul busolei are o orientare indiferentă. Cum îl pui, așa stă. Asta se întîmplă din cauză că la polii magnetici liniile de cîmp magnetic sînt exact verticale, deci acțiunea asupra unui ac magnetic orizontal este aceea de a-l înclina puțin într-un plan vertical, și nu de a-l roti în plan orizontal.

si mai important

meteor a scris:Dupa ce finisati,  ,  vreau cineva sa ma lamureasca ce este cu vuetul de dinaintea cutremurului, si din care cauza eu m-am trezit(se pare ca de dinaintea vuetului) ?!

Sa fie oare vuetul ca un rezultat al cutremurului (miscarii) care produce unde sonore, care inainteaza putin inaintea cutremurului (datorita vitezei sunetului mai mare) ?!

Cert ca vuet a fost, eu parca mai intens il auzeam ca si cum ar fi fost mai mult afara decit in casa.

omuldinluna a scris:


Din toata povestea asta, cel mai important, cred eu, este de retinut tot aspectul cantitativ. Aceste efecte (fluctuatii si deplasarea polului) sunt prea mici pentru a fi observate in cursul catorva minute, dupa cum spune AdiJapan, dar cu siguranta ar fi observabile in perioade mai lungi de timp.

CAdi a scris:Uite aici un alt film cu comportarea unei busole magnetice,
aproape exact cum am eu ,la Polul Nord ,in care se vede ca acul
busolei sta nemiscat ,iar daca il apropii de un cui sta de asemenea
nemiscat in directia cuiului.
Deci exact cum am zis eu . Sta nemiscat in pozitia in care il pui.

Filmul asta de ce nu l-ai dat pe post ca l-am gasit langa al tau ?