arcus(redirected from gerontotoxon)
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A dense and horizontal roll-shaped accessory cloud, with more or less tattered edges, situated on the lower front part of the main cloud.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
A low, horizontal cloud formation associated with the leading edge of thunderstorm outflow (i.e., gust front). Roll clouds and shelf clouds are both types of arcus clouds.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved