This year’s autumnal equinox occurs today at 07:50 UTC, which translates to 11:50 a.m. AKDT. On this day, fall begins in the Northern Hemisphere and spring begins in the Southern Hemisphere.
What’s an Equinox?
The word “equinox” comes from Latin “aequus,” meaning “equal,” and “nox,” “night.” On the equinox, day and night are roughly equal in length.
During the equinox, the sun crosses what we call the “celestial equator” — an imaginary extension into space of Earth’s equator line. The celestial equator was a friendly line of reference for me during the years I conducted sun and star fixes for celestial navigation.
“Autumn has caught us in our summer wear.”
–Philip Larkin, British poet (1922–86)
The equinox occurs when the sun’s center passes through this line. When the sun crosses the equator from north to south, this marks the fall equinox; when it crosses from south to north, this marks the vernal, or spring equinox.
Around the autumnal equinox, the sun rises later, and nightfall comes sooner. This ends with the December solstice, when days start to grow longer and nights shorter, which is why the winter solstice is more significant for a lot of people to celebrate (me included) that New Year’s.
“Autumn days come quickly, like the running of a hound on the moor.”
To many folks, equinoxes signify change. Change in the jet stream, change in temperature, change in light, change in activities. In last week’s column I posed the question: “What kind of winter will we have?” I suppose we need to get through fall first, but will fall bring crisp, cool weather or unseasonably warm weather like we experienced this summer?
Why do leaves
Cottonwoods, willows, alders and fireweed are donning colorful clothes these days. But that fall foliage isn’t due to current weather conditions, which is a common misconception. Leaves change color mainly because of the amount of daylight, or the lack of it.
As the autumn days grow shorter, the reduced light triggers chemical changes in deciduous plants. If you could look inside a leaf, you’d see that a corky “wall” form between the twig and the leaf stalk. This corky wall eventually causes the leaf to drop off in the breeze.
It’s not easy being green
The corky cells continue to multiply. Eventually they seal off the vessels that supply the leaf with nutrients and water. They also block the “exit vessels,” which trap simple sugars in the leaves. It’s a perfect storm: the combination of reduced light, lack of nutrients and no water add up to the death of the pigment chlorophyll, or the “green” in leaves.
Once the green is gone, two other pigments show their faces. These pigments, carotene (yellow) and anthocyanin (red), exist in the leaf all summer but they are actually hidden underneath summer’s greenery. They are masked by the chlorophyll which helps plants absorb sunlight.
It’s the sugar that’s trapped in autumn leaves by the corky wall that’s mostly responsible for the vivid color. This is why the foliage is so bright and sparkling after several bright fall days and more pastel during rainy spells. (Local photographers, take note).
What conditions bring the best fall colors?
While leaf-peeping is big business on the East Coast, Kodiak has its own version. This time of year, local photographers look for pockets of color in the form of a clump of red fireweed in Pasagshak or a hillside of golden willow on the Anton Larsen Bay road.
In general, a wet growing season followed by an autumn with lots of sunny days, dry weather and cold, frostless nights will produce the most vibrant palette of fall colors. This vividness is especially true of red leaves, such as low-growing bearberry plants on top of Pillar Mountain.
Of course, if freezing temps and a hard frost hit the area, it can halt the process within the leaf and lead to dulled-down fall color.
Also, our summer drought conditions may have triggered an early “shutdown” of trees as they prepare for winter, causing leaves to brown up and drop early from trees without reaching their full color potential. You can see this in some of our cottonwood trees. Cottonwoods are water-lovers and many stands have already turned crispy and brown.
By the way, can you balance an egg on the equinox? Well, there’s an old-wife’s tale that you can stand an egg on its end on the equinox. I’ve tried it, after my sister sent me a photo of 3 eggs standing vertical on her kitchen counter. Truth is, it’s not just on the equinox. Still, it’s fun to try.
My sister says brown eggs are easier to balance. Do you think she’s pulling my leg?
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