Changes

'''Ball lightning''' refers to mobile bright spheres sometimes observed during thunderstorms.  Most observations of ball lightning are made during thunderstorm activity, within a few feet of the ground.  A typical ball lightning is about as big as an orange or grapefruit, and lasts a few seconds.  Visual sightings are often accompanied by sound, odor, and permanent material damage. <ref>[http://istp.gsfc.nasa.gov/earthmag/magnQ&A4.htm NASA.gov]</ref>

'''Ball lightning''' refers to mobile bright spheres sometimes observed during thunderstorms.  Most observations of ball lightning are made during thunderstorm activity, within a few feet of the ground.  A typical ball lightning is about as big as an orange or grapefruit, and lasts a few seconds.  Visual sightings are often accompanied by sound, odor, and permanent material damage.<ref>[http://istp.gsfc.nasa.gov/earthmag/magnQ&A4.htm NASA.gov]</ref>

Very similar, if not identical phenomena, occur in submarines due to electric discharge of direct current across a circuit breaker, and in high-power electrical equipment.  Ball lightning is sometimes confused with St Elmo's Fire. St Elmo's fire is a corona discharge from a pointed conducting object, ''which must remain attached to a conductor'', and which usually lasts much longer than ball lightning.

Very similar, if not identical phenomena, occur in submarines due to electric discharge of direct current across a circuit breaker, and in high-power electrical equipment.  Ball lightning is sometimes confused with St Elmo's Fire. St Elmo's fire is a corona discharge from a pointed conducting object, ''which must remain attached to a conductor'', and which usually lasts much longer than ball lightning.

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[[Category: Science]]

[[Category:Science]]