Vail’s Curious Nature: Some say spring starts in February
Vail, CO Colorado
VAIL, Colorado –It’s not a spell check error. I do mean spreng, Vail Valley.
Spreng is the original form of spring, meaning to jump up or move quickly. In this connotation however, the word pertains to the new growth of plants, grasses and trees typically seen in temperate regions. Oh and by the way, we are two thirds of the way through spreng depending on which method (and interpretation) you use to determine the seasons.
Seasons are reckoned in one of three ways: astronomically, meteorologically or ecologically. The astronomical determination is the one that we’re most familiar with but use somewhat incorrectly.
Astronomical reckoning uses the solstices (referring to the northernmost and southernmost paths the sun takes across the sky) and equinoxes (equal length of nights in Northern and Southern hemispheres) as beginning dates for each of the seasons. Using this method, we’re supposed to count the solstices and equinoxes as the middle point, not the beginning point, of each season. In other words, March 20 should mark the middle of spring, not its beginning.
Using the astronomical method, spring more accurately begins around Feb. 3 and ends on May 5. This may seem an odd concept high in the Rockies but for populations living in Atlanta or Dallas, it is perfectly understandable.
The reason people count solstices and equinoxes as beginnings and ending instead of midpoints is referred to as thermal lag. Thermal lag is the period of time it takes for surface temperatures to catch up with insolation, or the amount and angle of sun in a particular region.
So although the Northern Hemisphere is subjected to the most direct and longest duration of solar radiation on June 21, the summer solstice, we don’t feel the higher temperatures until a month or so later. That’s why in Colorado July and August are our hottest months.
The second method for determining the change of seasons comes from meteorologists and simply groups months by three, according to average temperature. Using this method, June, July and August are the hottest and so are counted as summer. December, January and February are the coldest, or winter, and the months in between, March, April and May become spring by default. This method yields the first day of spring as March 1.
The third method for reckoning seasons uses ecological events such as the blooming of trees to mark the start of spring. Using this method, regions throughout the country have different spring dates that vary from late February to May. Needless to say, this method is fairly confusing.
In the United States, the generally accepted convention is to use the equinoxes and solstices as beginning points for the seasons. Using this method, spring began on March 20 (the March equinox) and will end on June 20 (the day before the June solstice).
Scientists say that it is more accurate to refer to these solar events by month name instead of seasonal descriptors such as vernal or summer because they are flipped in the southern hemisphere. The start of our spring is actually the start of fall for Australia, so calling it a vernal equinox would not make sense.
Enough about spring. If you can’t wait for summer to get here, the meteorological method states that summer starts June 1 while the correct use of the astronomical method would yield an even earlier start date of May 6. Both dates are well before the generally accepted start date of June 21.
I reckon it’s time to get those lawn chairs and beach towels out of storage.
Doug Dusenberry is the campaign director at Gore Range Natural Science School. Doug is passionate about the Colorado seasons but is anxiously awaiting this coming summer. (www.gorerange.org) The Gore Range Natural Science School’s Curious Nature column appears Mondays in the Vail Daily and on http://www.vaildaily.com.