Only positives come from restoring a coating on a metal roof and then maintaining that coating by re-coating the roof as necessary. An elastomeric acrylic coating acts like a shield, protecting the metal roofing system from the elements, including ultraviolet (UV) radiation, and ice and hail storms.
one hand clapping. The sound of one hand clapping is the sound of one hand closing quickly. The sound of one hand clapping is supposed to be a question with no answer. It is a clasic Zen koan given to students to aid in enlightenment by leading the mind into a cul-de-sac with no way out but enlightenment.
A 'thunder-clap', or the noise our ears hear (ranging from a sharp crack for nearby, short path-length lightning strikes to a long, low rumble for a distant, long path-length discharge), is caused by the rapid expansion (due to heating) of air in the lightning channel that the stroke passes through.