These have been mistaken for UFOs at times. The cloud formation in the troposphere occurs perpendicular to the wind direction. Gliders use it to get good lifts and create altitude and distance records

As the name suggests, a large hole is created in cirrocumulous or altocumulous clouds due to temperature of the water body below being too low.

These are caused when electrically charged particles from solar wind accelerate along the magnetic field lines into the upper atmosphere. Then these particles collide with gas atoms, creating the effect. The zone for 'Aurora' creation is 10 to 20 degrees from magnetic poles.

When the ice is compressed and the air bubbles are squeezed out, these waves are created. This blue ice is created because the light at the red end of the spectrum is absorbed.