Shelf cloud: a low, horizontal wedge-shaped arcus cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms), attached to the base of the parent cloud above it (usually a thunderstorm). Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent, boiling, and wind-torn. Roll cloud: a low, horizontal tube-shaped arcus cloud associated with a thunderstorm gust front (or sometimes with a cold front); roll clouds are completely detached from the base of the parent cloud above it (usually a thunderstorm). Sometimes roll cloud rises that much that it gets attached with the base of the parent cloud above it thus becoming shelf cloud. In my area they
usually occur a couple of times a year.
Date read as:
year-month-day-hour and minutes in CET (Central European Time). © SkyStef. |
