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hen you talk about winter precipitation to most Ohioans, the first image that generally comes to mind is one of snow, or just nasty wet gray days. Along the winter storm fronts where the forces of warm and cold air clash here, precipitation may fall in many forms other than snow and rain, even if for only a brief interval. Even from a clear blue sky.
( I'm not a native of this area but I am told... if you don't like the weather just wait, It will change any minute.
now and Rain, are not the only types of winter precipitation , only the most common.
The other winter members include: freezing rain and drizzle (glaze or hard rime), soft rime, ice pellets, ice crystals,
ice needles, snow grains and graupel. [ A small white ice particle that falls as precipitation and breaks apart easily
when it lands on a surface.] They are also known by a variety of local names in different regions: sleet, hail, soft
hail, snow pellets and diamond dust. I have not heard Diamond dust since I left Upstate New York.
cience 7, or Meteorology 101...
Most all forms of hard rain begin as ice/snow crystals in the clouds. If, as they fall, they travel through
a layer of air that has above-freezing temperatures, they melt or partially melt depending on the depth of
the layer and how warm it is. If they do not next enter a subfreezing air layer, then they fall as rain or a
mixture or rain and snow. But if they pass through a layer of subfreezing air before hitting the surface,
they may refreeze, partially refreeze, or super cool.
[ Remember when Mr. Shelageter used to put things in liquid nitrogen, and then pull them out and
break them like glass?] Yeah subfreezing, like that...
nd if the falling particles are caught in a series of updrafts [warm air rising] and down drafts [cold air falling]
and make multiple passes [looping] through the warm and cold layers, they may collect several layers of ice [Hail stones].
The two exception to the above are ice crystals and ice needles which are special forms of snow.
ce crystals may form late in the day under clear skies and light winds as the temperature drops and fall as soft showers.
Fluttering lazily downward, they glitter in sun or moon light and we call them diamond dust. Ice crystals form
at low temperatures (less than -18deg. C / 0deg. F) as, hexagonal plates and /or columns. [Think salt crystals,
or stubby pencils], as opposed to the delicate branched snowflake shape. When their diameter is less than 15-20
micrometres, crystal plates tumble randomly through the air as they fall. But when
the plates are larger, they fall so that their long dimension is parallel to the ground.
Forms of hard rain are rime and glaze.
here are two forms of rime: hard and soft. Hard rime and glaze are usually called freezing rain or drizzle. Both are formed
by supercooled drops which freeze on contact with a cold surface. Temperatures and rates of fall determine whether freezing
rain/drizzle will become glaze ice or rime ice. Meteorologists [those guys on the weather shows], classify transparent and
homogeneous ice forming on vertical and horizontal surfaces [electrical wires... tree branches being the common ones we notice],
as glaze. The amorphous, dense structure of glaze helps it to cling tenaciously to any surface on which it forms, causing
extensive damage across the region where it falls. In contrast, if the ice is milky and crystalline, it is termed hard rime.
Hard rime ice is less dense than glaze ice and does not cling as well, therefore generally inflicting only minor damage.
Soft Rime is deposited on cold surfaces by supercooled cloud droplets, [ fog ] rather than strictly falling onto it.
The buildup of soft rime ice usually leaves an opaque coating, which may point like a flag in the direction of the wind that deposited it.
oft rime is also often called hoar frost and is common at elevations where cold clouds move across the landscape.
Hard rains may fall either as showers or continuous precipitation, snow and rain, ice pellets may fall continuously or in showers.
Freezing rain/drizzle, snow grains and ice crystals usually fall as steady precipitation whereas showers are the dominant method
of fall for graupel...snow pellets and soft hail. Soft rime generally deposits on surfaces rather than falls.
"A hard rain's a-gonna fall," Bob Dylan lyrics, 1960s This reference was to the threat of radioactive fallout from a nuclear war.
Bob
Dylan, who was from Minnesota, probably saw his share of hard winter rains.
Being from up north myself, an artist and Photographer, I see these things a little differently than most Columbus natives.
Please enjoy my photos of the December 2004 Ice storm that hit Columbus, Ohio.
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