Confusion in the interpretation of standard-speed video observations of optical flashes above intense cloud-to-ground lightning discharges has persisted for a number of years. In Section 5.1, much of which has been published by Barrington-Leigh et al. [2000], high speed (3000 frames per second) image-intensified video recordings taken in 1997 are used along with theoretical modeling to elucidate the optical signatures of elves and sprites in video and in photometric arrays. In particular, the brief diffuse flash sometimes observed to accompany or precede more structured sprites in standard-rate video is shown to be a natural component of sprite electrical breakdown and to be due entirely to the quasi-electrostatic thundercloud field (sprites), rather than the lightning electromagnetic pulse (elves). This portion of a sprite has been named the ``sprite halo'' [Barrington-Leigh et al., 2000].
Section 5.2 relates the observation of sprites in close
association with negative cloud-to-ground lightning (
CG) on at
least two occasions above an unusual storm on 29 August 1998, as reported by Barrington-Leigh et al. [1999a]. Data
from high speed photometry, low-light-level video, and receivers of
lightning electromagnetic signatures in the frequency range 10 Hz to
20 kHz are used to establish the association and indicate that the
causative CG discharges effected unusually large vertical charge moment changes
(
) of up to 1550
in 5 ms. The existence of sprites caused
by CGs, rather than the regularly associated 
CGs, has
implications for sprite models and for strategic choices made
while undertaking sprite observations.
Section 5.3 discusses different time scales evident in
photometric measurements of sprites. Observed features
imply the existence of electric fields that are kept constant over
times ranging from 
1 ms to tens of milliseconds. In addition,
they may provide a means to remotely sense the electric field within
sprites.