The celebration of the equinox

After a very hot August and early September, conditions across the Inland Northwest have finally felt more like fall over the past week. Unfortunately, there was a lot of smoky air last week that sent air quality levels past 200, which is classified as “unhealthy for sensitive groups.” This week’s weather should have less smoke and haze as weak Pacific storms should mix up the air.

Fall officially arrives Thursday, Sept. 22, at 6:04 p.m. As I’ve mentioned in previous articles, we have the four seasons because the earth is tilted on its axis by approximately 23.5 degrees. During the summer, our planet is tilted toward the sun, resulting in longer daylight hours and a higher sun angle. As we move into September, the daylight hours become noticeably shorter, and on this Thursday, the event also known as the Autumnal Equinox, the entire planet will experience approximately 12 hours of day and night.

The reason the times are not exactly 12 hours apart on the first day of fall are complex. Our location in a particular time zone, elevation and the fact that the sun is not a singular point in space are some of the explanations. Here in Coeur d’Alene, we will have about 12 hours and 13 minutes of daylight on the official first day of fall. Our length of day won’t be close to exactly 12 hours until Monday, Sept. 26.

The Autumnal Equinox, the first day of fall, and the Vernal Equinox, the first day of spring, have been closely observed by ancient civilizations. In fact, there are structures that were specifically built to observe these astronomical events.

One of the most famous is the pyramid in Chichen Itza on Mexico’s Yucatan Peninsula, near Cancun. The Kukulkan Pyramid, also known as El Castillo, is certainly an impressive structure that was built thousands of years ago and is listed as one of the Seven Wonders of the World. The staircase of the region’s highest structure has 91 small steps and at sunset of the autumn and spring equinox, a body of light will form in the shape of a serpent on the pyramid and move down its steps to eventually reach the carved head of the serpent called Kukulkan. There are plenty of videos showing this event on the internet and people from around the world will come to see this incredible event in person.

Cliff, his son and I organized a Harris-Mann Weather and Commodity Seminar back in 1991 and had the opportunity to visit Chichen Itza. During that time, we were allowed to climb the structure and decided to make the journey. It was an amazing site to behold at the pyramid’s top, but I will admit, coming down those thin 91 steps was a bit unnerving. Today, tourists are no longer able to climb the pyramid, as officials closed it down after a deadly accident from someone falling down the stairs.

Perhaps the most famous ancient structure celebrating the equinoxes and the winter and summer solstices is England’s Stonehenge. During the first day of summer, or the Summer Solstice, the sun will align perfectly with the giant heel of Stonehenge. Researchers believed that this structure was built to use the sun to track the seasons.

There are other ancient structures that are dedicated to the observations of the seasons. They have been found in Egypt, Peru, Ireland, Malta, Cambodia and even in the U.S. The closest one to our region is located at Chaco Canyon in New Mexico. At this location, there have been many structures that have been discovered over time that track the movement of the sun. Fajada Butte is the most popular and during the equinoxes and solstices, detailed carvings will produce a perfectly positioned dagger of light on a wall.

In terms of our local weather, we should see some showers later this week, but conditions are expected to turn dry once again. There is an increasing chance of more rain at the end of the month, but the moisture may not be enough to push our September total to normal levels. Our normal precipitation for September is 1.49 inches, and Coeur d’Alene has only picked up around a quarter-of-an-inch for the month. At the Spokane International Airport, a meager 0.04 inches of rain has been reported for September as of the weekend.

Assuming that September’s rainfall will end up below the 1.49-inch average, this will be the third month in-a-row with below-average precipitation. June was a wet month with 5.11 inches, but most of the moisture fell during the first half of the month.

As Cliff and I have said many times, during this period of extreme weather, we should continue to flip from dry to wet and vice-versa for the foreseeable future. Therefore, conditions should turn much wetter and cooler later in the fall season.

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Contact Randy Mann at randy@longrangeweather.com.