midtskogen wrote:Source of the post The halo is formed when light gets deflected through countless ice crystal, and the minimum deflection is just under 22 degrees, regardless of the distance to the light source.
Yeah, I know the angle that a light rays is deflected through a crystal only depends on the geometry of the crystal. It makes sense to me that if the crystals are illuminated by parallel rays, then with each crystal deflecting the light by some angle, the viewer will see the light deflected through crystals which are that same angle from the source. But I thought if the rays were not coming in parallel, then the same deflection angle would lead to a different halo angle seen by the observer. Otherwise it seems odd that the deflected ray would reach them. (It would mean more than 22° deflection in this case, if the halo was still seen to be 22° in size).
I agree on the need to know the crystal geometry for noctilucent clouds -- please share whatever information you get back!