Friday, December 21, 2007

The winter solstice, Hoarfrost and Abraham

Get ready to drool over the seed catalogues, because there will be more and more sunlight.
On Sat., Dec. 22, 2007, 1:08 A.M. EST (06:08 UT), marks the solstice—the beginning of winter in the Northern Hemisphere and summer in the Southern Hemisphere The shortest day of the year, respectively, in the sense that the length of time elapsed between sunrise and sunset on this day is a minimum for the year. **** Solstice information.
As for the Hoarfrost I must tell you it was Abraham that alerted me to this. You might want to check his Blog, fabulous bird photos. So after doing some research, spurred on by Abraham, these are a few neat things I learned. Thanks Abraham!
Hoarfrost: *************
A deposit of interlocking ice crystals (hoar crystals) formed by direct sublimation on objects, usually those of small diameter freely exposed to the air, such as tree branches, plant stems and leaf edges, wires, poles, etc., which surface is sufficiently cooled, mostly by nocturnal radiation, to cause the direct sublimation of the water vapor contained in the ambient air.
Now this information is Totally Kewl **********
Grow Your Own Frost!
You can make your own hoarfrost crystals if you have a cold, wind-free location -- for example, an unheated outdoor shed. Just plug in a hotplate and heat an open pan of water over a low heat for a day or two. You'll want to heat the water without heating the whole shed, so it helps if it's good and cold outside.
You may want to provide a branch or some other artistic surface above the pan for water vapor to condense onto. How the crystals grow will depend on the air temperature (see the Snowflake Primer), so you may find different types of hoarfrost crystals on different days. If you see something interesting when you try this, take some pictures (see Photographing Snow for useful techniques) and send me an e-mail.
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Really a neat site I think!
One can distinguish between some types of hoar frost, depending on where it forms. For example, air hoar is a deposit of hoar frost on objects above the surface, such as tree branches, plant stems, wires; surface hoar is formed by fernlike ice crystals directly deposited on snow, ice or already frozen surfaces; crevasse hoar consists in crystals that form in glacial crevasses where water vapour can accumulate under calm weather conditions; depth hoar refers to cup shaped, faceted crystals formed within dry snow, beneath the surface.

2 comments:

Old Wom Tigley said...

Fantastic Post... I have yet to follow the link 'D' but I will do.. this sounds like great fun.

I'd like to take this chance to wish you and your family a very Happy Christmas. I may not get the chance to comment here again before Christmas Day so just in case... Have a great festive family Christmas time and keep warm, keep safe, and may you all keep smiling. *<:O).
from
Tom, Jane, and our friend Big Peter

DeeMom said...

"O" it was Abraham that gave me the name of the Frost picture I took, so thanks to him, ey?