17th April 2006

Cloud-to-Cloud Lightning

Source: Excerpt from The Book " Weather "

Cloud-to-Cloud Lightning

  • Distribution:
    Worldwide, except
    Antarctica; common in the tropics.

  • Height: Anywhere within the height range of a cumulonimbus cloud.

  • Cause: Electrical discharge between one thundercloud and another, or within a single thundercloud.

  • Associated Weather: Heavy rain or hail, strong winds from associated thundercloud.

    Cloud-to-cloud lightning is the most common form of lightning. Most often it occurs within a cloud, and involves electricity passing between the negatively charged base of the cloud and its positively charged upper levels. This internal lightning stroke often illuminates the cloud from within. A large flash can produce a spectacular snapshot of an entire cumulonimbus, which may remain visible for up to half a second if there is a succession of strokes up and down the leader path.

    Less frequently, cloud-to-cloud lightning involves an electrical discharge between opposite charges in two adjacent clouds. This will normally occur between the positively charged top of one cloud and the negatively charged base of the other.

    Because cloud-to-cloud lightning normally occurs at higher altitudes than cloud-to-ground lightning, it may be seen from some distance away, particularly at night. Indeed, a large cumulonimbus cloud will be visible up to 200 miles (320 km) away if the surrounding terrain is reasonably flat.

    Thunder is usually audible only up to around 20 miles (32 km) from the lightning stroke that created it. This means that cloud-to-cloud lightning often appears to the observer as a "Silent Storm", with frequent flashes illuminating the sky amid eerily silent surroundings.

  • Acknowledgement due: John W. Zillman, William J. Burroughs,
    Bob Crowder, Ted Robertson, Eleanor Vallier-Talbot and Richard Whitaker.

    The Airline Pilots Forum and Resource