Seasons happen.

In spite of all the other unpredictable things in life, including bizarre weather, the seasons arrive every three months on a predictable schedule.

Today we welcome fall or autumn.  This is the period of the year when we will lose even more daylight and by the time we reach the final day of this season, the noontime sun will be at its lowest point and there will be just under 9 hours of daylight between the morning sunrise and the afternoon sunset.

December 20th will mark the final day of fall with winter to follow.  The term equinox is derived from the idea of equal day and night.  The reality is everywhere on the planet has nearly equal day and night today, but our 12-hour day won’t actually occur until Monday.

The rate of light loss will begin to slow after the equinox. TimeandDate.com

COOLING AIR

Temperatures will also continue to tumble in this season.  Even though daylight reaches a minimum during autumn, our temperatures won’t really bottom out until we’ve had about a month of winter.  We’ve actually been cooling for nearly two months (on average).  Already, normal highs are in the 60s.

Average temperatures take a tumble in autumn. Dave Epstein

Fall is quite dramatic here in the Northeast.  In Maine, we can have warm temperatures even reaching the 80s,  as we will next week, but it can also snow.  Snow can accumulate as early as the first half of October, but more likely we won’t see our first flakes until late in that month or November. In some years snow doesn’t arrive until December, but it’s highly unlikely we won’t see some in the autumn season.

HERE COME THE COLORS

The decreasing light, more than the cooler air, causes plants to start shutting down in preparation for winter. We can already notice foliage changing and this will continue to spread south and east in the coming weeks.

Peak foliage is a rather subjective idea since some people love the landscape when all the leaves have changed and others enjoy a blend with some green still on the trees.  There are certain trees that change very early – like many maples – and if you wait until you see the word “peak” to go leaf-peeping  you will miss those colors.

Foliage is already worth viewing in northern areas and the higher elevations. Foliage Network

WHY SEASONS HAPPEN IN THE FIRST PLACE

Seasons occur because the Earth is tilted on its axis at 23.5 degrees.

As the Earth revolves around the sun, different amounts of sunlight reach the surface of the planet at different angles and for varying amounts of time.

Those two variables – length of daylight and angle that sunlight hits the Earth – give us our different seasons.

At the equator, both daylight and angle of the Sun don’t change much. That’s why tropical areas around the equator pretty much have the same weather all year.

Here in Maine the angle of the sunlight and the amount of daylight have dramatic swings.  In the summer we have over 15 hours between sunrise and sunset; in winter that number goes below 9 hours.  In summer the sun is nearly 70 degrees above the horizon at noon, in winter it’s only about 23 degrees above the horizon – an incredible shift bringing about temperature changes of over 100 degrees from winter to summer. Pretty awesome!

The fall equinox arrives September 22nd – that’s today! NOAA