Where do moon dogs happen?

Inquiring minds want to know: Where exactly do these so-called "moon dogs" occur? Are they a rare astronomical phenomenon, perhaps only visible in remote parts of the world with clear night skies? Or do they occur in more populated areas, accessible to amateur astronomers with a keen eye for the unusual? I'm particularly fascinated by the conditions that must be present for a moon dog to manifest itself. Is it a combination of specific weather patterns, lunar phases, or perhaps even geographical location? Clarifying the "where" of this mysterious sighting is sure to capture the imaginations of skywatchers across the globe.