Extreme Week

The first eleven days of December were all below
average, some well below average.  Since
the middle of the month we have only seen one day below average which occurred
a week ago today.   Because the first
half of the month was so much colder than the second half was warm, the month
will still finish below the long term average for temperatures. 

Big swings in temperatures are common place
in this climate.  You rarely go through
an entire season, be it winter or summer, with temperatures consistently above
or below average, it is usually a mix of the two extremes. 

Current indications would suggest that we are
probably going to see more big swings in temperatures in the near future.  We seem to be headed for a brief cold snap
the next few days quickly followed by what may be a January thaw late in the
week

Blue Snow

I recently received an
email asking why snow appears blue occasionally. White light contains all the
colors of the rainbow ranging from the shorter wavelength color of blue, to the
longer wavelength color of red. When white light passes through ice or snow the
longer wavelength colors, the reds and oranges, are absorbed leaving the shorter
wavelength colors of purple and blue to be transmitted to your eyes.


Normally,
it takes a relatively thick piece of pure ice to absorb enough red light to
leave only the blue light behind (a glacier would be a good example of this).
The reason you can see the effect in snow at fairly shallow depths is because
light is bounced around repeatedly among the snow flakes, losing a little red at
each bounce sometimes giving snow a light bluish hue.

Winter Solstice

At 12:08 AM this morning the sun‘s
direct rays were over the Tropic of Capricorn marking today as the Winter Solstice. I have always enjoyed the two solstices each year. Why you ask? It’s
all because of the sun angle.

Most people think of the winter solstice as the "shortest day of the year" and the summer solstice as the
"longest day of the year" (are they not all 24 hours?), but I think of
the solstices as the highest and lowest sun
angles of the year.

Today at solar
noon (which is never at noon locally because of our position
in the time zone) the sun
will reach its maximum height above the southern horizon at only 19 degrees. With the snow on the ground reflecting what little heat the sun
is giving us this time of year it’s no wonder our weather can get very cold around the
holidays.

Hoar Frost

When warmer and relatively moist air moves into this area during our cold season low clouds and fog usually develop. During this process, the warmer air gradually cools to its dew point, or in other words, the warmer air mixing with the colder air produces a relative humidity of 100%.

Fog, even when temperatures are well below freezing, is usually composed of mostly liquid cloud droplets (supercooled water). When these liquid droplets touch objects below freezing, ice crystals begin to grow on the colder surfaces. The interlocking ice crystals become attached to branches of trees and other objects and slowly grow into hoar frost.

This crystal growth turns trees and any other object that is exposed to these supercooled water droplets white, giving the landscape that classic "winter wonderland" look.

Abundant Snow

After receiving a bit more than a foot of snow in the past week some of you are probably already tired of the snow.  If it makes you feel any better we are not the only ones getting snow.  Some parts of the Twin Cities have also received around one foot this week. 

Montreal, Quebec reported 12 inches of snow from the same system that moved through this area last Saturday.  Portland, Maine received nearly 9 inches earlier this week with many reports of 12 to 18 inches falling in northern Maine. 

There is now snow on the ground along and north of a line from Bismarck to Sioux Falls to Des Moines through Chicago.  Plus, most of the interior sections of New England also have a snow cover. 

So in other words, we are not the only ones with sore backs from shoveling. 

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