tube-cloud-3

Roll clouds were part of an amazing sunrise in Scotland County early Tuesday morning, September 13th.  A roll cloud is a low, horizontal, tube-shaped and relatively rare type of arcus cloud, a category of low cloud formations.  Roll clouds form near advancing cold fronts.  A downdraft from the advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud.  When this happens uniformly along an extended front, a roll cloud may form.  They differ from shelf clouds by being completely detached from a thunderstorm base or other cloud features.  They usually appear to be “rolling” about a horizontal axis.

tube-cloud-4

tube-cloud-2