The Magnetic Universe

22 Mar 2010

http://www.australasianscience.com.au/bi2009/301Gaensler.pdf  .. from this site a pdf article can be accessed, Bryan Gaensler, 'The Magnetic Universe' - magnets are everywhere, even in lodestone, and for centuries navigation relied on the fact a compass will always point north. Migrating birds use magnetic fields and this is because the entire earth is a weak magnet. The magnet inside the earth lines up almost exactly with it's spin axis and therefore just as a paper clip will be attracted to the end of a toy magnet so too a compass needle is attracted to the pole. The earth's magnetic field deflects energy charged particles on the solar wind - which only approaches the surface near both poles when they flouresce in the atmosphere and generate aurorae. Magnetism on the Sun is responsible for sun spots, solar flares, and coronal mass ejections.

The sky is full of magnetism - where does it come from? He then enters into a history of how and when magnetism in space was discovered, and it's relevance to the spiral nature of the universe. He then brings up Faraday and the theory of polarisation of light. It has been found that galaxies create magnetism very quickly - confirmed by Swiss and American research. It seems there is something fundamental missing from current theories concerning where magnetism comes from and how it evolves as galaxies evolve. A new generation of radio telescopes is being built - including the Square Kilometre Array Telescope (SKA). This will be used to measure Faraday rotation via background polarised light. Hence, it is thought science will finally determine how magnetic fields emerge, evolve, and possibly die. Astronomers are only now beginning to appreciate the unique role that magnetism plays in many of the most complicated and perplexing processes in astrophysics and cosmology.

Charles Chandler (http://charles-chandler.org/Geophysics/Tornadoes.php ) has an article, 'An Integrated Electromagnetic and Thermodynamic Approach to the Study of Supercell Thunderstorms and Tornadoes' ... March 18th, 2010. The common assumption that electromagnetism is too weak to influence the behaviour of supercells is challenged. The air in a supercell is moving rapidly and a portion of that air is recirculating in a continuous loop. It contains charged particles. The flow of these particles constitutes a closed loop electric current. The movement of charged particles generates magnetic fields that influence the movements of the particles - even though the magnetic field is actually weak. That does not mean it can't dominate an open air thermal system - and he offers an explanation for tornadoes. The defining characteristic of a tornado is that it attaches itself to the surface of the earth which is not explicable in fluid dynamics. Previous research concluded that an electric current could cause a discharge vortex but not a tornado - as the airflow is distinctly different. Chandler approaches the problem from another angle and goes on to explain how it is possible for an electric current to induce an opposite charge within the earth and attract the charge within the supercell so the tornado will run along the ground.

Weather Eye in The Times last week had an interesting story about Maracaibo in Venezuela. It seems that Francis Drake, the sea dog, in 1595, under the cover of darkness, attempted an assault on the port but a sudden blaze of lightning gave away his position to the Spanish garrison - and he abandoned the venture. A similar nocturnal lightning display in 1823 revealed the position of Spanish ships to republicans and led to the defeat of the Spanish and independence for Venezuela. It seems that night time lightning at Maracaibo is common - and can be seen 40 miles away. Lake Maracaibo, behind the port, is associated with extraordinary amounts of lightning lasting several hours on 140 to 160 days of each year. Annually, this amounts to a million lightning discharges in one small region of the earth. At the same time such electric storms are extraordinarily quiet as they are cloud to cloud discharges miles above the ground and the thunder cannot be heard. It is unknown why this particular spot is a magnet for lightning.