Words on Weather & Climate — March 18, 2010


by Craig James

What a great way to start out the month of March. It was certainly windy and gloomy this past weekend but prior to that, every day from the 2nd through the 8th had 93 percent or more of possible sunshine with three of those days receiving 100 percent of possible sunshine. Compare that to February when only one day had 100 percent of possible sunshine and on 17 days, we received no sunshine at all.

Since the snow cover was slow to melt, golf season didn’t start quite as early as last year when I golfed on March 6.

I did practically have to use a hammer to get the tee into the still partially frozen ground and there was ice in one of the cups, but hey, it beat sitting indoors and writing a newspaper article. I was able to golf all the way to December 2 for golf in 10 of the 12 months of 2009.

Last year, we hit the first 70 degrees of spring on March 17. Looking at the last 116 years of records, it turns out we have a 51 percent chance of reaching 70 in March, and a 74 percent chance of hitting 60 degrees. That means in one out of every four months of March, the temperature never gets as warm as 60. That’s depressing.

With all of the cold weather in the southern states this year, the tornado season has gotten off to a very slow start. In fact, it looked as if we were going to see the only month of February on record with no tornadoes reported in the entire country. However, according to the National Weather Service, a weak tornado that lasted all of three minutes was spotted, in of all places, California on the 27th to spoil the record. There have only been twelve tornadoes so far this month.

Since we are on daylight saving (not savings) time now, it is staying light until 8 p.m.. Astronomical spring arrives on the 20th this year, which is of course when there is equal day and equal night across the globe. However, if you look at sunrise and sunset tables you will see on that date we have 12 hours and nine minutes of sunlight. Why not exactly 12 hours?

According to timeandate.com, “The geometric center of the sun’s disk crosses the equator during the equinox, and this point is above the horizon for at least 12 hours on earth. However, the sun is not simply a geometric point. Sunrise is defined as the instant when the leading edge of the sun’s disk becomes visible on the horizon, whereas sunset is the instant when the trailing edge of the disk disappears below the horizon. These are the moments of first and last direct sunlight. The disk’s center is below the horizon during this time.”

In addition, “atmospheric refraction causes the sun’s disk to appear higher in the sky than it would if earth had no atmosphere. The disk’s upper edge is visible in the morning for several minutes before the disk’s geometric edge reaches the horizon. Similarly, the disk’s upper edge disappears in the evening several minutes after the geometric disk passes below the horizon.”

What this means is that day and night are each equal to 12 hours a few days before the spring equinox and again a few days after the autumnal equinox. If you really want your eyes to glaze over and put yourself to sleep, read this article http://www.larry.denenberg.com/earliestsunset.html on why the earliest sunset and latest sunrise do not occur on the winter solstice and vice versa in the summer. You will be amazed to learn that near the equator, the earliest sunset does not occur near the winter solstice, it occurs in November.

What we do know about March is that it usually snows in West Michigan. In fact, Grand Rapids averages about 10 inches of snow in March. We haven’t had any measurable snow yet but in almost all El Nino years, which this one has been, we get a period of false spring like we have had, which is followed by another week or so of cold with snow before spring arrives to stay. Sad to say, I think that will happen this year too.

Craig James has been retired since July1, 2008, after 40 years of broadcasting television weather. He was chief meteorologist at WZZM-TV for 12 years and chief meteorologist at WOOD-TV for 24 years. He is a graduate of Penn State University, where he received a Centennial Fellowship Award. He was also honored as a Fellow of the American Meteorological Society.

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