• Question: Why does lightning strikes?

    Asked by alan1421 to Anil, Blanka, Cees, Emma, Mike on 29 Jun 2012.
    • Photo: Blanka Sengerova

      Blanka Sengerova answered on 29 Jun 2012:

      I’ve definitely looked this up – on here http://www.weatherquestions.com/What_causes_lightning.htm which is something that is worth mentioning. In science, when you quote other people’s work and information that you’ve read in books, it is important to reference their material.

      The website says that “Lightning is produced in thunderstorms when liquid and ice particles above the freezing level collide, and build up large electrical fields in the clouds. Once these electric fields become large enough, a giant “spark” occurs between them (or between them and the ground) like static electricity, reducing the charge separation. The lightning spark can occur between clouds, between the cloud and air, or between the cloud and ground. ” which seems good enough explanation to me. Does it satisfy you?

    • Photo: Emma Trantham

      Emma Trantham answered on 2 Jul 2012:

      This made me think back to my school Physics! 🙂 I just wanted to add a few points to Blanka’s great answer.

      As she said, an electrical field starts to build up in the clouds – the top of a cloud (the bit away from the earth) ends up with a different charge from the bottom of the cloud (so the top of the cloud is positive whilst the bottom is negative).

      You might have seen this charge difference before – have you ever rubbed a balloon against your hair and then seen how it can cling to other things like walls? Rubbing the balloon made it negatively charged and so it now will cling to anything positively charged (because opposites attract). We often describe this as static (which is really the short way of saying static electricity).

      Sometimes this can be a bit more extreme – have you ever had a static shock? Well this shock was a little spark of electricity.

      Lightning is also a spark of electricity only it is much much bigger! The negative part of the cloud is a bit unstable so it wants to get rid of this negative charge. And that’s what lightning is – the cloud discharging its electrical field.

      Forked lightning is when the discharge happens between the cloud and the ground. Sheet lightning is when this occurs between different clouds (so we just see the reflection of the clouds).

      Does this make sense?

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