Arcus cloud Arcus cloud An arcus cloud is a low, horizontal cloud formation, usually appearing as an accessory cloud to a cumulonimbus. Roll clouds and shelf clouds are the two main types of arcus. Arcus clouds most frequently form along the leading edge or "gust fronts" of thunderstorm outflow; some of the most dramatic arcus formations mark the gust fronts of derecho-producing convective systems. Roll clouds also may arise in the absence of thunderstorms, forming along the shallow cold air currents of some sea breeze boundaries and cold fronts. A shelf cloud is a low, horizontal, wedge-shaped arcus cloud. A shelf cloud
Timeline of events associated with Anonymous Timeline of events associated with Anonymous Anonymous is a decentralized virtual community. They are commonly referred to as an internet based collective of hacktivists whose goals, like its organization, are decentralized. Anonymous seeks mass awareness and revolution against what the organization perceives as corrupt entities, while attempting to maintain anonymity. Anonymous has had a hacktivist impact. This is a timeline of activities reported to be carried out by the group. According to radio host Hal Turner, in December 2006 and January 2007 individuals who identified themselves as Anonymous took Turner's website offline, costing him thousands of dollars in bandwidth bills.