Welcome to Naturalist’s Corner.  Today we’re going to talk a little about fall.  Actually there’s nothing much you can do about a fall after it’s started – once you’ve lost your footing you’re pretty much under the jurisdiction of the laws of physics until you land.  So the best way to deal with fall is just to watch where you put your feet.

          Now that we’ve gotten that out of the way and since we still have some space left to us, let’s talk a bit about autumn.  Autumn is that time of year, which precedes winter in the seasonal schedule.  It gradually moves us from the sweltering heat of summer to the crisp days of frozen fan belts.

The official start of fall is heralded by the autumnal equinox which takes place on September 20 or 21 – depending on whether it’s a leap year, what day Easter is on and adjusting for the Congressional Monday Holiday Bill.  At any rate, the equinox is that day which is made up of nearly equal parts day and night…along with a bit of dawn, a smidgen of disk and just a dash of salt to taste.  This phenomenon occurs twice a year; once in the spring as the days get longer and once in the autumn, as the days again grow shorter.  This is described in its name by the Latin words “equinox”, which means “equal night” and “autumnal”, which means, um, autumn.

Fall, however, is not so much a day on the calendar as it is a time of the year.  It is a transitional season, which begins on that first cool morning you have to wear your jacket out of the house.  Followed by that second cool morning when you have to remember where you left your jacket since you had to drag it along after the temperature shot up to 85 degrees by 10:00 A.M.  Yes, autumn is not a definitive season like summer or winter but a time of change.  It is a gray area, which is not really warm and not really cold but rather a slipping from one to the other.  In truth, autumn was never really considered a season in past societies…that concept was invented and initiated by snowmobile dealers and snowblower salesmen in order to have a basis for pre-season sales.

Autumn sees the leaves drop from the trees and the temperatures slip downward.  Frosts begin to settle and plants droop.  Eventually the snows will drift to the ground.  What do all these things have in common?  They’re all FALLING, get it?  Leaves FALL.  Temperatures FALL.  Snows FALL…  Oh, sure, the leaves turn brown and plants turn brown so it could have been called brown instead of fall, but temperatures are not brown and snow isn’t brown – except in some highly industrialized areas and in the case of volcanic activity.  Anyway, this change is so dramatic we call the season fall.  Besides, it’s easier for kids to spell than “autumn” – where did that “n” come from, anyhow?  What’s the purpose for that?

The shortening days and the cooling temperatures come about at this time of year because of the position of the earth in relation to the sun.  At this time of year the planet, in its journey around the sun, tilts on its axis.  This can be understood by driving your car down the highway and around a curve at, say, 80 miles an hour.  You will notice as you drive around the arc that your car will lean heavily as you follow the road to the next straightaway.

On second thought, don’t try this on your own, since you may slide into the ditch and cause $3464.83 damage to your vehicle.  Anyway, you can see by this experiment that the planetary tilt is simply caused by the earth coming into a really sharp turn as it races around the sun.

This slight tilt our home experiences causes the light from the sun to strike the Northern Hemisphere at a less direct angle, thereby allowing less energy to reach the Earth.  This could be more easily understood by imagining the amount of collision energy exerted on a car by driving straight into a row of fenceposts at, say, 80 miles per hour, which might totally wreck a vehicle beyond repair.  By comparison, the same vehicle at the same speed sliding into the fenceposts at a less direct angle, like from off a curve, would receive only $3464.83 in damage.  That is kind of why it gets cooler in the fall – because nature can’t drive.

The smaller amount of daylight experienced in the fall is also attributable to this same tilt of the Earth.  Because of the new angle, the sun rises above the horizon later in the morning and sets earlier in the evening.  Another reason contributing to this effect is governmental intervention; that is, the change from Daylight Savings Time back to Standard Time.  What this encompasses is removing the hour of daylight they tacked onto the end of the day in the spring.  Then they send it to the Southern Hemisphere where they got it from in the first place – and that’s why the length of the seasonal days is varied in the different hemispheres.  It’s some kind of hemispherical, international treaty thing.

Finally, the cooling temperatures and the shorter days combine to cause the most dramatic transformation of the season – the changing of color and the subsequent shedding of leaves by the trees.  What causes this theatrical display?  Seems to me that the trees would want to keep covered in the winter to keep warm and shed in the spring like mammals.  But then trees are not mammals, which is a good thing or we would all be raking up clumps of fur in the spring instead of leaves in the fall and the darn stuff would blow all over the place and you couldn’t wear any dark sweaters or light jackets ‘cause the hair would be all over and…well, you get the idea.

Let’s get back to the leaves and that color change and falling thing they do.  These steps are taken for the purpose of water conservation.  It seems that in the winter the freezing of the soil reduces the supply of moisture to the roots of the trees.  To experience evidence of this, simply stick a straw into an ice cube and suck real hard.  See what I mean?  Anyway, since leaves have a large surface area they loose a great deal of moisture to evaporation.  In an attempt to avoid fatal dehydration, the tree, signaled by a combination of shortening hours of daylight, cooler temperatures and Christmas decorations in department stores, creates a barrier of cells where the leaf stem joins the twig.  This slowly causes the leaf to starve and die.  The attachment to the twig weakens and the leaf eventually falls to the ground…  In effect, the tree strangles the leaf and flings it from the branch.  Fickle, isn’t it?

Scientifically, the color change occurs from the same action.  Deprived of nutrients and moisture, the leaf can no longer form new chlorophyll.  As the old chlorophyll breaks down, the green color disappears.  The leaf then takes on the red, orange and yellow colors, which were always present but were masked by the green of the chlorophyll.

Besides, if somebody strangled you, you’d turn pretty colors, too.