During the 21st century approximately 4.9 percent of all central solar eclipses — those eclipses where the moon crosses directly in front of the disk of the sun — fall into the hybrid classification.
In most cases, an annular-total eclipse starts as an annular, or "ring of fire" eclipse, because the tip of the moon's dark shadow cone — the umbra — falls just short of making contact with the Earth; so the moon appears slightly smaller than the sun producing the same effect as placing a penny atop a nickel leaving a ring of sunlight shining around the moon's edge.
Then the solar eclipse transitions to total, because the roundness of the Earth reaches up and intercepts the shadow tip near the middle of the path, then finally it reverts back to annular toward the end of the path.
However, as pointed out by the renowned Belgian eclipse calculator, Jean Meeus, the hybrid eclipse of Nov. 3 will be a special case: here the eclipse starts out as annular, then after only 15-seconds it will transition to a total eclipse, and then it remains total up to the very end of the eclipse path. The last time this happened was on Nov. 20, 1854 and the next such case after 2013 will occur on Oct. 17, 2172.
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http://www.space.com/23442-rare-hybrid-solar-eclipse-explained.html
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