A Giant Wave in the sky?! What is it?

The clouds called "arcus" are a phenomenon that we rarely ever see, for this reason few know about them. 

The same goes for the woman who filmed this video clip in a small town in Georgia (USA). What she filmed is a huge bank of arcus clouds which consist of a formation of low clouds with ripped or ragged shapes (ragged shelf clouds) that had appeared right in front of her house.

By the way ... this formation of clouds always precedes the arrival of a thunderstorm. Impressive!