Shadow bands are “elusive ripples of alternate light and dark, flitting over the ground or the sides of buildings”
(to quote from the section on them in The Under-Standing of Eclipses).
Dr. Satyendra Bhandari, of Ahmedabad in India, wishes to organize an “International Shadow Band Campaign” during the approaching total eclipse. If you expect to be in or very near to the track of totality on August 21, he encourages you to write to him: email@example.com
He will no doubt send instructions on the simple observations needed, and some of his interesting thinking about shadow bands. He is working on a “Manual of Shadow Band Observations” and once shared a draft copy of it on SEML (the eclipse listserve), and is also preparing an introductory book on the subject. He regards shadow bands as one of the important effects of eclipse on Earth environment. The transition between daylight and darkness at sunset is “routine” and gentle, but the transition at the onset of total eclipse is a “shock” to the atmosphere, through which the Moon’s shadow is moving with supersonic speed.