Minute by minute, winter is very much a numbers game

For meteorologists in the Upper Midwest, winter runs from Dec. 1 to the end of February, usually the coldest 90 days of the year.

On the first meteorological day of winter this year, Budd Lake at Faribault, Minn., Lake Washington in LeSueur County, Lotus Lake in Chanhassen, and Long Lake at Vergas froze over, along with hundreds more Minnesota lakes.

If we don't count seconds, the Twin Cities and area have the least amount of daylight, at 8 hours and 46 minutes, for seven days between today, Dec. 18 and the 24th. During these seven days our planet in its elliptical orbit around the sun has slowed down to the point we only lose or gain daylight in seconds daily.

By Christmas Day we will have gained a full minute of daylight, a nice gift, and by Dec. 31 four minutes more.

By astronomical calculation, winter arrives Monday at 4:02 a.m. At that time the earth will reach the point in its revolution about the sun so that the North Pole is inclined 23.5 degrees away from the sun. It's the winter solstice, and we in the Northern Hemisphere have our longest night and shortest day.

At noon on the first astronomical day of winter, the sun is 22.5 degrees above the horizon in Mankato, 21.5 degrees in Minneapolis and St. Paul, and only 18 degrees in International Falls. On this shortest daylight day of the year Winona receives about 8 hours and 54 minutes of sunlight, the Twin Cities area 8 hours and 46 minutes, and people at International Falls must get by with only 8 hours and 15 minutes.

Usually there is a lag time of 30 to 40 days after the period of minimum solar radiation, which allows the ground and air to cool down as much as possible. Statistically, Jan. 25 is our coldest day of the year.

With new ice, some snow cover, and maybe a surprise white frost, December can provide some of the year's most dramatic landscapes.

Beavers are active inside their lodges, feeding on bark from tree branches they stored underwater in the fall. Whitetail deer begin dropping their antlers. Ring-necked pheasants feed in corn stubble and pick up roadside gravel, which goes into the gizzard and helps grind up food in the first stage of digestion Bald eagles hunt fish where open water prevails. Cedar waxwings feed on the fruit of junipers, mountain ashes, and crabapple trees.

Jim Gilbert's observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.