Halos on the surface of frozen puddles were captured
again by Dávid Hérincs in Egyházasrádóc, Hungary. His previous observations can
be seen in an earlier post on Halo Vault ( 1 ). On 6 and 7th February, abundant
rainfall and the cold air mass settling afterwards, created ideal conditions for
the formation of frost crystals on icy puddles. On the first day, only the
subsun, subparhelia and possibly lower tangent arc were seen. On the 7th,
however, more complex halo forms showed up on a huge puddle. Dávid Hérincs made
a video of the observation.
As
he noted, the huge puddle had three separate ice surfaces, with different angles
of inclination, and thus the sunlight did not meet the ice crystals at the same
angles. This could be the reason why the halos appeared on these surfaces
slightly differently. The observer marked these three parts of the puddle in
frames cut from the video, and noted that on surfaces 1 and 2 the sharp curving
halo arc had white brightenings at a distance further from the previously observed
subparhelia, but approximately in line with the subsun (see: first photo). On surface 3, the lower
sun pillar was not observable, but a halo form that looked like a subparhelic
circle appeared (second photo).
Since these three icy surfaces were located next to one
another, at times the halos belonging to them were observed simultaneously (third photo). Any
comment and help with the identification of these halo forms are welcome. Further
images can be seen on the observer’s Hungarian language website ( 2 ).
About
a year ago, in February 2018, Dávid Hérnics also captured a halo of prismatic
colours, when he looked almost vertically at the ice surface towards the nadir
area. This might be a patch of the sub-circumzenith or circumnadir arc, similar
to the one observed by Jari Piikki in 2008 ( 3 )
 |
| Surface halos in Budapest, Hungary, on 19th February 2018. |
The
full account of Piikki’s observation can be read in Marko Riikonen’s and Jarmo
Moilanen’s post ( 4 ) where
they also shed light on the problems of nomenclature, and whether the sub-
prefix should be used.
