More Evidence...
Another thing pointing to something happening that is affecting the convection within the earths core is changes to the rate of wander of the earth's magnetic field poles, and the emergence of strong magnetic anomalies in the earth's magnetic field.
Most people think of the earth's magnetic field like that of a giant bar magnet. This view is overly simplistic. There are minor poles and anomalies in the earth's magnetic field. There are multiple sources for these. Magnetic fields frozen in rocks spreading at mid-ocean rifts can be of a polarity that opposes the earth's main magnetic field and can cause a localized weakening of that magnetic field. Since this rock moves very slowly, these anomalies are stable and long term and also tend not to be of a high magnitude.
The Suns solar wind and magnetic field lines carried with it also interact and distort the earth's magnetic field lines. During periods of solar magnetic storms these cause the earth's field to wiggle and jitter. This can cause effects ranging from temporary deflection of compass needles from their normal direction to power outages as changing magnetic fields induce very low frequency currents into power lines. Because transformers have very low impedance at these low frequencies, they conduct large amounts of current through their windings either damaging the transformers or opening fuses causing blackouts. These anomalies are very temporary and correlate with solar coronal mass ejections.
There is another type of anomaly that relates to internal changes in the electro-magnetic dynamo at the earth's core. This type of anomaly manifests itself differently than the other two. It changes more rapidly than those caused by magnetic fields frozen in rocks, but less rapidly than solar magnetic storm induced anomalies. It involves minor poles that often rise to substantial magnitude and have a polarity opposing the main magnetic field.
It is believed that the process of magnetic field reversals begins with these types of anomalies, they strengthen until they eventually become the predominate magnetic field replacing the original main field with a new field of opposite polarity. The view that the earth's magnetic field simply flips by reducing in strength to zero and then rebuilding in the opposite direction is too simplistic. Instead, minor poles form and grow in strength as the main poles decrease in strength and eventually these become the dominate field. The earth's magnetic field never totally goes away but it does become weaker, more complex, and less organized for a period of time during the transition.
There are indications presently that the earth is starting to undergo such a magnetic reversal. The earth's magnetic field has dropped to approximately 50% in strength over the last hundred years. The rate of wander of the main north and south poles have also increased substantially during this time frame. Lastly the formation of substantial magnetic anomalies signals a shift. In particular one anomaly over the southern tip of Africa is so intense that it almost entirely cancels the predominant magnetic field over regions of the southern Atlantic ocean. The unfortunate result of this has been radiation damage to satellites over this region that previously were protected from radiation by the earth's magnetic field.
Based upon this rate of decline many people speculate that the reversal will not occur until sometime in the next century. However, magnetic fields frozen into the rocks spreading from the mid-ocean rift tell of a different story, those fields indicate the process is more logarithmic than linear. Once the change starts, the rate of change increases and so the change can be expected much sooner.
It isn't clear that the field will actually reverse, there are instances recorded in the spreading sea floor in the past where the magnetic field reduced in strength but then rebounded in the same polarity as it was prior to the reduction in strength.
What is clear is that changes are occurring in the earth's magnetic field are happening and the rate of change is increasing substantially in a very short time frame.
Understand that these fields are believed to be caused by a self-excited electro-magnetic dynamo in the earth's core. Changes in this field would suggest changes in the convection patterns in this core.
Most people think of the earth's magnetic field like that of a giant bar magnet. This view is overly simplistic. There are minor poles and anomalies in the earth's magnetic field. There are multiple sources for these. Magnetic fields frozen in rocks spreading at mid-ocean rifts can be of a polarity that opposes the earth's main magnetic field and can cause a localized weakening of that magnetic field. Since this rock moves very slowly, these anomalies are stable and long term and also tend not to be of a high magnitude.
The Suns solar wind and magnetic field lines carried with it also interact and distort the earth's magnetic field lines. During periods of solar magnetic storms these cause the earth's field to wiggle and jitter. This can cause effects ranging from temporary deflection of compass needles from their normal direction to power outages as changing magnetic fields induce very low frequency currents into power lines. Because transformers have very low impedance at these low frequencies, they conduct large amounts of current through their windings either damaging the transformers or opening fuses causing blackouts. These anomalies are very temporary and correlate with solar coronal mass ejections.
There is another type of anomaly that relates to internal changes in the electro-magnetic dynamo at the earth's core. This type of anomaly manifests itself differently than the other two. It changes more rapidly than those caused by magnetic fields frozen in rocks, but less rapidly than solar magnetic storm induced anomalies. It involves minor poles that often rise to substantial magnitude and have a polarity opposing the main magnetic field.
It is believed that the process of magnetic field reversals begins with these types of anomalies, they strengthen until they eventually become the predominate magnetic field replacing the original main field with a new field of opposite polarity. The view that the earth's magnetic field simply flips by reducing in strength to zero and then rebuilding in the opposite direction is too simplistic. Instead, minor poles form and grow in strength as the main poles decrease in strength and eventually these become the dominate field. The earth's magnetic field never totally goes away but it does become weaker, more complex, and less organized for a period of time during the transition.
There are indications presently that the earth is starting to undergo such a magnetic reversal. The earth's magnetic field has dropped to approximately 50% in strength over the last hundred years. The rate of wander of the main north and south poles have also increased substantially during this time frame. Lastly the formation of substantial magnetic anomalies signals a shift. In particular one anomaly over the southern tip of Africa is so intense that it almost entirely cancels the predominant magnetic field over regions of the southern Atlantic ocean. The unfortunate result of this has been radiation damage to satellites over this region that previously were protected from radiation by the earth's magnetic field.
Based upon this rate of decline many people speculate that the reversal will not occur until sometime in the next century. However, magnetic fields frozen into the rocks spreading from the mid-ocean rift tell of a different story, those fields indicate the process is more logarithmic than linear. Once the change starts, the rate of change increases and so the change can be expected much sooner.
It isn't clear that the field will actually reverse, there are instances recorded in the spreading sea floor in the past where the magnetic field reduced in strength but then rebounded in the same polarity as it was prior to the reduction in strength.
What is clear is that changes are occurring in the earth's magnetic field are happening and the rate of change is increasing substantially in a very short time frame.
Understand that these fields are believed to be caused by a self-excited electro-magnetic dynamo in the earth's core. Changes in this field would suggest changes in the convection patterns in this core.
posted by Nanook at Saturday, December 30, 2006
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