A rare type of cloud, called a roll cloud, stretched across the sky in Timbercreek Canyon, Texas, last week and a woman who spotted the phenomenon captured it on video.
The woman viewed the tube-shaped cloud from her home at sunrise last Monday, and her husband, Todd Mask, posted the video on YouTube. Mask described the cloud as a horizontal vortex that looked like "an ocean wave rolling in."
The stunning and somewhat ominous formation lies low in the sky. According to the National Weather Service, roll clouds are usually associated with a thunderstorm gust front. They are relatively rare and are completely detached from the thunderstorm base or other cloud features.