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.
