Airplane Optics

Flights and tall buildings or mountains are some of the best ways to see a different class of atmospheric optical phenomena, namely those which lie opposite to the sun. In the images below, diffraction in the cloud droplets produces a multi-ringed glory that surrounds the shadow of the airplane. 

With the clouds slightly farther away, the shadow of the airplane gets smaller in respect to the size of the glory, which remains roughly constant. 

Sometimes, when one can see a glory, the conditions are right also for producing a cloudbow (a type of fogbow) farther away from the airplane's shadow. A few supernumerary arcs are also visible in the image, on the inside of the main cloudbow arc.

Some similar images of mine were published as the Optics Picture of the Day some time ago. 

Antisolar halos

Although I'm a quite avid atmospheric optics observer, I rarely have to look down to see such phenomena. However, on a flight I took not too long ago, I was fortunate enough to see a few rare halos. 

The interesting thing is that the subhorizon halos are like a reflection of the those above the horizon, and the very cool thing about it is that this reflection actually takes place inside the ice crystals that create these optical phenomena in the first place (on a lower horizontal plate).  However, the sub- and over-horizon halos are not perfect reflections of each other.

The image below shows the antisolar point (bright spot in the lower right of the image), a portion of the subparhelic circle going horizontally through the antisolar point and the parry antisolar arcs, seen as two lines going through the antisolar point at an angle of about 60 degrees from the horizontal. 

Les Cowley's excellent website does a much better job at explaining this stuff. 

I'm just very happy that I saw them: