Saturday, 25 February 2017
A reflection subsun - or just rain streaks?
However, when this observation was submitted to Taivaanvahti and the reflection subsun interpretation was suggested, it was also quickly put in question by Tero Sipinen on the basis of the apparent low altitude of the stuff in which the effect appears. It seemed like ice crystals could not have occurred under those dark clouds in the middle of the summer.
Atmospheric sounding data for that day, checked by Sipinen, gives additional support: freezing point was reached not until 4 km altitude from the ground. The clouds against which the pillars show up, are clearly lower down and thus couldn't have possibly precipitated ice crystals.
So I am wondering, are these just sun lit rain streaks? According to Pitkänen, the clouds are remnants from thunder, so some rain can still be present. Actually, the intense orange twilight in the photo is probably due to falling rain. And in general, we are not used to seeing halos under cumulonimbus clouds.