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
The Cloud of Unknowing short word rather than a long one. A one-syllable word such as "God" or "love" is best. But choose one that is meaningful to you. Then fix it in your mind so that it will remain there come what may. This word will be your defence in conflict and in peace. Use it to beat upon the cloud of darkness above you and to subdue all distractions, consigning them to the "cloud of forgetting" beneath you. Editions of related texts include The Cloud of Unknowing The Cloud of Unknowing (Middle English: "The Cloude of Unknowyng") is an anonymous work of