The End Of Sumer…Kinda, Sorta

Summer offically lasts until September 21st, the date of the autumnal equinox, when the sun’s rays are directly over the equator.  However, in meteorology the seasons are simplified into three month blocks.  The months of June, July and August are meteorological summer.  So starting September 1st, Wednesday, meteorological autumn begins.

Whether you start your autumn on Wednesday, or you wait until the third week of September, you can’t deny that summer is losing it’s grip on our weather.  It still may be hot and humid, and your air conditioner is still going to get a workout for awhile, but the seasons are transitioning.  Look at the number of minutes of daylight we now have as compared to just two weeks ago.  There is nearly 30 minutes less daylight today than there was back in mid-August.  We’re losing daylight at a rate of 2 to 3 minutes a day.

As that is happening, the sun angle is decreasing as well, meaning less of the sun’s energy is reaching the earth. The highest point above the horizon the sun reaches is 78 degrees on June 21st, the first day of summer.  That is when the sun is the strongest.  By July 4th, the sun angle has decreased to 73 degrees.  Today, at it’s highest point in the sky, the sun angle was 63 degrees.  By Halloween it will be down to 40 degrees, and on December 21st, the first day of winter, and the shortest day of the year, the sun angle will be a measly 31 degrees.  Remember, the smaller the sun angle, the less energy is reaching the earth.  Less energy from the sun means less warming of our atmosphere.

Our atmosphere cools first most dramatically in the northern latitudes where the sun angle is lower even in the summer compared to those of us in the south.  This leads to pools of cooler air that move south into the United States behind the first cold fronts of the season.  At first the fronts are fairly weak (although last week’s was a nice doozy), but they get colder and colder as we move deeper into autumn.

So even though the calandar says we still have three weeks of summer, know that autumn is lurking just around the corner, even if you can’t quite feel it yet.

Rick

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One Response

  1. I can feel it already.

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