The Four Seasons

 

At a meeting the other day someone casually mentioned that we were rapidly approaching March 21, which she told me was the first day of spring. Naturally, that set me to wondering about why so many people have unthinkingly come to associate the Vernal Equinox with the onset of spring. Or the onset on winter with the Winter solstice and so on. There are two easy answers. First, a number of ancient societies are widely known to have observed certain celestial events and tied them to religious and agricultural celebrations. The Egyptians, Romans, Druids, and Mayans are good examples. Second, it’s my opinion that TV meteorologists have been the main culprits responsible for this identification by touting it on TV during their daily weather spiels. Which actually is very strange since they, more than many others, should know better.

But first a little note of clarification about the Vernal Equinox itself. Vernal is from ver, the Latin word for spring. Equinox is Latin for equal night, by which the Romans meant that on that day there were an equal number of hours during the day and night, which although is not exactly true it is widely believed to be so. What really happens is that equinox occurs twice each year when the center of the Sun is directly vertical over the Earth’s celestial equator (with a declination of 0°), occurring each year around March 20/21 and September 22/23. But the key question is why does that happen?

That question brings us to Earth-Sun relations and the world of astronomy. Actually, we experience celestial events known as equinoxes and solstices because the Earth’s axis is inclined with respect to the plane of the ecliptic, about 23½° from the vertical (celestial poles), a condition known as obliquity. It is that inclination, the Earth’s rotation on its axis, and its procession around the Sun that result in the climatic changes that are so prominent across the surface of the Earth.

So, on or about March 20/21, the Sun’s vertical rays strike the equator at a 90° angle and the Earth experiences an approximately equal number of hours of day and night. From that day until June 21/22 the hours of daylight in the Northern Hemisphere grow longer and the nights shorter while the reverse pattern pertains in the Southern Hemisphere. As befitting their astronomical nature, those events (equinoxes and solstices) are experienced in the very same manner and at the same time all over the Earth.

It should be obvious from the explanation above that both equinoxes and solstices, as astronomical events, depend on obliquity, the Earth's rotation on its axis, and its revolution about the Sun. But if spring, summer, fall, and winter were astronomical events they also would be experienced in the very same manner and at the same time all over the Earth. But, are they? Here’s a specific example. Does the onset of spring occur on the same day in Fairbanks, Alaska, as in Key West, Florida? Average daily March temperatures in that part of Alaska are still around freezing while those in Key West are in the low to upper eighties. Are those locations experiencing the same season? Or what about Maiquetia, Venezuela? It’s in the Northern Hemisphere and therefore according to popular wisdom should be having its first day of spring on March 20/21. But its daily average March temperatures are in the mid-nineties. Is that also spring? Actually, the season of spring does not exist anywhere in Venezuela, nor does winter as we know it. So, what’s going on?

Confusion, that’s what’s happening. We have been mislead by TV meteorologists and others who, without cranking up their brains and thinking about the situation, tell their gullible audiences that spring arrives every year precisely on March 21. And that’s sad because they should know the difference between an astronomical/celestial event and a climatological one. They are not the same and never will be despite uninformed people claiming they are.

Okay, when is the first day of spring? Who knows? Since spring is the transition between winter and summer its onset depends on regional and world weather patterns that vary from year to year. Consequently, spring is early some years and late in others. The good news is you can empower yourself and pick whatever day you want to celebrate spring. You’re not limited to March 20 or 21. When you want to celebrate spring you pick the day, line up a virgin to sacrifice, light the bonfire, chill your favorite booze, and have at it. And while you’re at it, do the world a favor and throw a TV meteorologist on the bonfire and save the virgin for another day.