Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: TUESDAY, March 20, 1990                   TAG: 9003202674
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A1   EDITION: METRO 
SOURCE: Associated Press
DATELINE: WASHINGTON                                 LENGTH: Medium

TO DATE OR LATE? SPRING HOPES INTERNAL

"The first day of spring is one thing and the first spring day is another. The difference between them is sometimes as great as a month," observed the late Henry Van Dyke of Princeton University.

Calendars proclaim March 20 as the "first day of spring." But to weather and climate professionals, spring arrived March 1.

Who's right?

"There has always been a division of opinion as to where to place the boundaries and the middles of the four seasons," reports Guy Ottewell in The Astronomical Companion.

In one system the equinoxes and solstices that mark the movement of the sun are considered seasonal boundaries, while other systems consider those dates to be seasonal midpoints, he says.

And while the federal government has managed to regulate most aspects of life in one way or another, even putting three different federal agencies in charge of time, there is no "bureau of the seasons."

Climatologists simply divide the year into four three-month seasons, with spring arriving each March 1.

The popular perception of spring beginning March 20 is based on the decision reached about a century ago by calendar printers to mark the seasons with the dates of the solstices and equinoxes.

In those days calendar makers usually printed almanacs too, and those featured the movement of the sun, moon and stars. That made it convenient to designate spring as beginning with a special date - the vernal equinox.

That's the date when daylight and darkness are nearly equal as the sun crosses the equator on its apparent trip north. This year, it occurs this afternoon.

That system of dividing the seasons apparently originated about 70 B.C. with the astronomer Geminus of Rhodes.

Spring, by the calendar method, lasts until the summer solstice - the northernmost point reached by the sun - which comes June 21 this year.

That day, the first day of summer for many Americans, is known as midsummer in much of Europe and great bonfires and celebrations are held on Midsummer's Night.

Richard Inwards, a leader of England's Royal Meteorological Society late in the last century, said the use of the solstices and equinoxes to mark seasons was illogical.

More reasonable, he believed, was the system used in the Middle Ages in Europe, using saints' days to mark the seasons. Spring, by that reckoning, begins on St. Peter's Day, Feb. 21, and lasts until May 24.

The medieval reckoning of summer lasting from May 25 to Aug. 23 helps explain why June 21, the first day of summer on American calendars, is known as Midsummer's Day in Europe.

Using the equinoxes and solstices as midpoints of seasons means the seasons begin on what are known as the cross-quarter days, between the solstices and equinoxes, Ottewell reports.

By that reckoning spring began on Groundhog Day, Feb. 2, and is now about half over.

Many astronomers consider spring the first season and in ancient times it marked the new year rather than having that celebration in midwinter as is done now.

For the record, the three federal agencies keeping track of time are the U.S. Naval Observatory, which operates atomic clocks; the National Institute of Standards and Technology, which defines the exact length of units of time; and the Department of Transportation, which is in charge of the changes from standard to daylight time and back again. That next occurs April 1.