Here's a report of gossamer masses startling people living in the Macedon Ranges shire of Victoria, Australia. The ability of young spiders to balloon is made possible by super-strong major ampullate silk, the silk araneomorph spiders use to rappel and to construct the strongest lines of their webs. Jumping spiders use it as their safety line. You can read more about ballooning in Chapter Five of Spider Silk, "Triumph Over Thin Air." One of my life's goals is to witness such a mass gossamer waft.