The story behind spring

Spring officially arrived yesterday at 8:33 a.m. in Coeur d’Alene and the rest of the Inland Empire. In the Southern Hemisphere, it is now their fall season as they are coming out of summer.

Most of you probably learned in school that we have seasons because Earth is tilted on its axis by approximately 23.5 degrees. In winter, the Northern Hemisphere is tilted away from the sun. This is why we have shorter daylight hours and a lower sun angle.

By the start of summer on June 21, the Northern Hemisphere is tilted toward the sun, allowing us to receive more direct solar radiation and hotter weather. Distance from the sun has very little to do with seasonal changes in temperature, as Earth is actually closer to the sun during our winter season, by about 3 million miles. It’s the tilt that makes all the difference for our four seasons.

However, in the Southern Hemisphere, some will argue that the heat is more intense during their summer season as skin cancer rates in Australia are some of the highest in the world. The higher rates of skin cancer may also be due to the annual fluctuation of the ozone hole over Antarctica.

The first day of spring is also known as the spring or vernal equinox. The word “equinox” comes from the Latin words meaning “equal night.”

This is an astronomical event when the sun is directly overhead at Earth’s equator. On June 21, 2022, our first day of summer, the sun will be directly overhead in the Northern Hemisphere at 23.5 degrees North, the Tropic of Cancer, which is the first day of astronomical summer. Residents here in North Idaho will never see the sun directly overhead as we are too far to the north with a latitude that's approximately 47.7 degrees North.

Then in September, we observe the Autumnal Equinox, or the first day of fall, when the sun is once again directly overhead at the equator. By next winter, the sun will be overhead at 23.5 degrees South, or the Tropic of Capricorn, which is why we get the shorter daytime hours.

During the equinoxes of both spring and fall, Earth’s tilt has little effect based on our position in the orbit around the sun. At these times, every point on our planet has about 12 hours of day and night.

The reasons 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.

I’m certain that many of you have heard the notion about being able to stand raw eggs on end, and perhaps a broomstick, during the first day of spring and fall. Most say it’s folklore and legend. Einstein and other scientists pointed to no scientific reason that the equinoxes will cause any gravitational anomaly.

I tried this once and couldn’t make it work, but there a few readers sent me pictures of their success. Standing raw eggs on end takes a lot of patience with the right shape of eggs to make it work properly, at any time of year. My patience ran out quick when I tried to stand an egg on end, but a rough surface or an egg that is a little bumpy might have better results.

By the way, the first day of “meteorological spring” was on March 1. The months of March, April and May are used for the spring calculations because it’s easier to compare the seasonal and monthly statistics. They're also based on the temperature cycles rather than Earth’s position relative to the sun.

Local Outlook

In terms of our local weather, moisture totals have been good across the Inland Northwest while many areas to our south, especially in California, are hoping for more rain.

The winter of 2021-22 in Coeur d’Alene was one of the shortest in history, especially in terms of snowfall. According to Cliff’s records, since Jan. 8, only 6.5 inches of snow has fallen in Coeur d’Alene. The first 20 days of this month had no snow in the lower elevations. Only three other years since 1895 have been snowless in Coeur d’Alene during this time.

Cliff and I see more storms for the Inland Northwest into at least early April. However, most of the moisture will likely come as rain in the lower elevations. There’s still a chance that some of these storms could bring snow to Coeur d’Alene and surrounding regions, but it’s going to be very tough to reach our seasonal normal of 69.8 inches.

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Contact Randy Mann at randy@longrangeweather.com