in By Diana Thottungal

Water is wonderful stuff, but in the winter it becomes almost magical. Flowers on how it is and how big the Sometimes water in a stem freezes already is, which is why there are always Cold and and splits the stem. It only happens bumps and ridges on big . They when the air is at temperature can curve, too. You’ve probably already combine to produce or below and the soil has not frozen yet. seen this on icicles that face east or west After the stem has split, capillary action with the sun on only one side during an amazing array pushes more up and out into the most of the day. The icicle will curve freezing air, enlarging the feathery flowers. away from the sun as in the picture of solidified water above. Icicles can form anywhere, even Two in the Garden that might on pine needles. forms. form frost flowers are blue salvia (salvia azurea) and periwinkle (vinca minor). Frozen …rime Frozen fog is called rime and is the Credits result of moist foggy air touching cold Gelee Blanche: http://upload.wiki- surfaces. It condenses and freezes, form- Water in the Winter sky media.org/wikipedia/commons/8/85/ Camille_Pissarro%2C_Gelee_blanche ing a or sometimes that When the sun is low in a clear winter _%28Hoarfrost%29%2C_1873.jpg look like bits of . snow sky, with just a few wispy (cirrus) clouds Here’s the surprise…many snowflakes, around, there’s a chance to see a halo, Tashiro Pond photo © Hiroki Suzuki. romantic, beautiful snowflakes form and on either side of the halo, bright Reprinted by permission. More of Mr. It comes in hard and soft versions. Suzuki’s work can be seen at http:// Hard rime is found on the side of a tree around a core of ! Then they spots called sundogs. homepage2.nifty.com/hsuzuki/english/ that faces the , doesn’t shake off grow, depending on the weather, to all Crystallized Dew – Hoarfrost easily (as would snow) and has a whitish kinds of shapes, like the plate, den- The cirrus clouds are made of , and photos permission of James drite and sectored plate above. Then the air around them also has ice in little Carter from the website Ice Yard 08 Sometimes when you step outside in the morn- look. at http://my.ilstu.edu/~jrcarter/ice/ ing after a clear frosty night in early or ice needles they continue to change until they flat hexagonal plates. If the plates are yard-2008/ late fall, the edges of leaves and grass blades are Soft rime can look like hoarfrost, soft Frost flowers are related to ice needles, become icy lumps. falling helter-skelter, the dog will just be trimmed with a lacy edging of . This is and white. Glaze, which is clear and a kind of upside down icicle that forms a bright spot, but if they are falling with Ice Needles from http://commons.wiki- media.org/wiki/File:Shimobashira_01.jpg called hoarfrost and happens when dew or water glassy, is not a form of rime; instead, it under the same conditions. If the the flat edges parallel to the ground a vapor freeze, usually below the regular water is the result of . ground is just a bit above freezing and spectrum will be visible.e Snowflake images © Kenneth G. Lib- freezing point (super-cooled). the air is below freezing, the frozen brecht, who has an excellent website at surface bits get pushed up by capillary http://www.its.caltech.edu/~atomic/ The photograph of Tashiro Pond with snowcrystals. A snowflake formation Since cold air is denser than warm air, it flows morning fog (above left) is the best I action. Then that bit freezes, and so on. chart is available from the Alaska Lake downhill so that the hoarfrost forms in low areas have seen illustrating fog condensing The result is needles of ice rising from Ice and Snow Observatory Network at or hollows. You can see this effect in Camille Pis- near trees, forming rime. the ground. http://www.gi.alaska.edu/alison/ALI- SON_Science_Snow.html. saro’s painting (above), Gelee Blanche (Hoarfrost). An easy way to remember the difference icicles Halo and Blurry Sundog near Rochester, Hoarfrost may also be called silver frost or white between hoarfrost and rime: Icicles are much more complicated than MN © 2005 Diana Thottungal frost. An unfortunate aspect of hoarfrost is that •Rime forms inside freezers just dripping water that freezes. The sun Diana Thottungal is a naturalist at the if it forms on top of deep snow it can lead to •Hoarfrost forms outside freezers on has to warm some snow, which melts Eloise Butler Wildflower Garden. . frozen food taken out on a humid day. and drips, but how far it drips depends

4 5 Icicle Theory, Practice and Weirdness

By Diana Thottungal The theory part is pretty easy. Sun, or heat escaping from the attic, warms piled up snow on the roof. Snow melts and starts to drip down. But the air is still cold and freezes the drip. Voilá, an icicle is born. Out in the woods, snow can be piled on dead leaves that have not yet fallen or on conifer needles, but the effect is the same. Leaves or needles that are busy photosynthesizing release and radiate heat the same way poorly insulated attics do. End of story? No. Icicle Tips: They look pointed but Barred really are tiny owl inverted cups that hold the drops as they form. Photo by Curved Icicles: These do make sense. If one side Photo by Tammy Mercer of the icicle is consistently exposed to the sun, the Cheryl Ciampa water stays melted, or gets melted on sunny days, Barred owl Great horned owl producing a curve that bows in on the sun side and out on the shade side. January Mating ritual

March Just laying their eggs Chicks are hatching Bumps and Ridges: They look random but aren’t. First, the distance of the bumps from peak Chicks are hatching Chicks are growing wing By fall most of the April and tail feathers, wandering to peak is consistent. Second, they apparently about the nest young will be vary in number according to the hardness of the independent of their Cavity nests can get very Chicks may be perched in water. And third—most amazing—it seems that May crowded, chicks may be branches near the nest, where parents and leave the perched in nearby branches they exercise their wings these ripples move upward as the icicle grows! territory. This is a Summer Young are busy learning to fly and hunt for themselves Branches? In very still dangerous time for air, an icicle can develop them because they Fall Young will be independent and leave the territory a tiny branch. And, if still lack experience. they can grow from a At the Eloise Butler discovered one of these raptors that prey on their roof or a leaf, they can Wildflower Garden we have heard and seen own. If you can follow the noise, you may just also grow from a leafless both species of large owl, but the great horned sight one of these big beautiful owls. tree or shrub branch, as owl is more frequently heard and most likely the Wikipedia picture at this site shows: http:// nests nearby. When a large mob of crows or blue —Tammy Mercer is a part-time naturalist who teaches on en.wikipedia.org/wiki/File:Icicles.jpg. Saturday morning bird walks at the Garden. jays makes a racket it is usually because they have For more information about icicle research, please see: http://www.mendeley.com/research/experiments- morphology-icicles-9/ References http://www.insidescience.org/current-affairs/1.1854 Ehrlich, Paul R., David S. Dobkin and Darryl Wheye. 1988. The Birder’s Handbook: a Field Guide to the Natural History of 5 North American Birds. Simon & Schuster Inc. NY, NY. —Diana Thottungal is a naturalist at the Stokes, Donald and Lillian. 1989. Guide to Bird Behavior, Volume Three. Little, Brown and Company. Boston, MA. Eloise Butler Wildflower Garden