Ask A Scientist© Weather Archive

 >   name        Sebastien
 >   status      other
 >   age         20s

 >   Question -  First excuse my English cause I speak french
 >I heard that lightnings strike from the ground to the clouds
 >Is that true?

>Dear Sebastien-
>
>In response to your question about lightning, this is a copy of an answer to
>a similiar question I posted a few days ago...
>
>
>You are correct in assuming that lightning can "strike" from the ground up.
>In fact, lightning does strike from different directions with each stroke..!
>The development of a bolt of lightning is very interesting. I won't go into
>all the details here, but a cloud-to-ground lightning bolt begins from the
>cloud in a series of "stepped leaders." As these leaders near the ground, a
>powerful "return stroke" of positive charge rushes up from the ground (at a
>speed up to 60,000 mph, or about 1/3 the speed of light) to meet the stepped
>leader. These static charges travel back and forth between the cloud and
>ground until the electrical potential is neutralized.
>
>Three types of lightning are common... cloud-to-ground, cloud-to-cloud, and
>in-cloud. So lightning can travel up, down, and even sideways..!
>
>Wendell Bechtold, meteorologist
>Forecaster, National Weather Service
>Weather Forecast Office, St. Louis, MO

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>Sebastien,
>
>Lightning develops as a result of a concentration of charge on the ground 
>and an opposite charge in the cloud. A stepped leader starts from the 
>ground and
>a leader meets it a few hundred meters above the ground. This ionizes a path
>for a lightning stroke, which goes up to the cloud from the ground (electrons
>stream from the cloud to the ground) and energy is transferred from the
>cloud to the ground.
>
>David Cook
>Argonne National Laboratory

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