Paul Bartlett wrote:

I have been an observer in eastern England since 1960 and never seen
these before today. As the temperature was below zero they settled and
so I could see them easily.
Now does this count for climate purposes as snow? I seem to remember
the code figure being 78 or 79 not 77 (snow grains). I have seen the
magic of plate like crystals when fog fell to the ground and really made
it glitter.
I estimate the cloud base to be about 200FT AGL and guess at the tops
being 2500FT with the whole lot below freezing.
Cheers
Paul

In December 1962, there was a fall of ice needles over Northants, Beds,
Hunts, and, I've heard, other parts of East Anglia. I can't remember the
date but it started in the morning at about 10 o'clock to half past. I know
the time because, when it started, I was at Bedford bus station waiting for
a bus to take me to RAF Wyton. It was foggy, sky obscured, when quite large
snowflakes started falling. Almost immediately, breaks appeared in the fog,
with large patches of blue sky, showing that there was no cloud above the
fog. The flakes were composed entirely of ice needles. When I arrived at
Wyton, I recall (vaguely) that the fog had dispersed, but snowflakes were
lying on the ground.

According to my 1961 edition of Notes for Scientific Assistants, the ww-code
for ice prisms (formerly "ice needles") is 76.
Also from that publication:
Definition: A fall of unbranched ice crystals, in the form of needles,
columns or plates, often so tiny that they seem suspended in the air.
Description: The crystals are visible mainly when they glitter in the
sunshine; they may then produce a luminous pillar or other halo phenomena.
This precipitation rarely occurs in the British Isles.
Cloud of origin: St or fog, or the prisms may form under a clear sky.

I've described in another thread about an ice fog I saw about 25 years ago
in Bracknell that had the associated optical phenomena but I don't know
whether the crystals were in the form of needles.

--
Graham Davis
Bracknell