[Part 3 of 6] To the unititiated, and viewed entirely out of context, the right portion of this scene could look like one of ominous, imminent, extreme danger:  one side of a very close, large tornado, churning along right behind the trees in the dim twilight.  It's just an illusion!  Instead, it's a shelf cloud moving overhead, lower in elevation than the midlevel cloud deck on the left side.  … [Read more...]

[Part 2 of 6] The blue-hour arcus cloud, rushing out from the tail portion of a deep and well-organized complex of thunderstorms to the north and northeast, pushed ahead rapidly in the morning twilight, yielding this strange, otherworldly appearance.  With natural light still somewhat scarce, faint Norman city light to the west imparted a peculiar reddish hue to a bit of the shelf cloud's … [Read more...]

[Part 1 of 6] Strong convective gust fronts in the sunrise hour can yield spectacular shelf clouds, as they force lift of boundary-layer air that is optimally stabilized by a nighttime of cooling.  This can yield some wild and weird visual effects, especially in the "blue hour" of early twilight.  With trees blocking the view of the horizon, and of the underside of the arcus, the cloud formation … [Read more...]