Blue Edges of the Half Orbs

I took the photos below on February 14, 2018 and March 19, 2018.  We see some of the strange half-orbs that I occasionally get (with fully round orbs being much more common). Both of the half orbs have a blue edge.

Below is another example from March 16, 2018.

An interesting speculation is that such photos show an orb in the process of appearing, hence the lack of full roundness.

There was no fog, mist, rain or precipitation on these nights.