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Unusual Lightning

St Elmo's fire

A blue-green glowing discharge high in the air would seem strange to anyone.

To sailors, it was a good omen, because it often appeared at the end of a storm. This caused the glow to be named after the patron saint of sailors, Saint Erasmus, or St Elmo.

St Elmo's fire appears around a pointed metal conductor, in a high electrical field. On sailing ships it appeared around the metal bands at the tops of masts. Today it can also be seen around lightning conductors on buildings, and airplanes (especially the wingtips). In a very strong thunderstorm, St Elmo's fire can sometimes even be seen around blades of grass.

Ball Lightning

Many people have reported seeing ball lightning. However no-one is sure exactly what it is. Some people believe that it is a ball of plasma that is somehow trapped by strong magnetic fields.

Whatever ball lightning is, many scientists now accept that it is real. Ball lightning normally appears as a freely floating glowing ball, about the size of a grapefruit. Sometimes the ball is seen to pass through walls or ceilings. It does not appear to be dangerous.

Ball lightning
Ball lightning
© Museum Victoria Australia