During this week, in our northern hemisphere, the winter season will officially end, and give way to spring.  This is known as the vernal equinox, when, in the earth’s revolution around the sun, neither pole is tilted toward the sun, which passes over the zenith in the sky, at the equator, and days and nights are each 12 hours long, all over the world.

The same thing happens around this time, in September, the autumnal equinox.  The 23 degree tilt of the earth’s axis is what causes seasons.  In winter, the sun is lower in the sky.  Its heat has to pass through more air, which reduces the amount of heat reaching the surface.  In summer, with it being high in the sky and its heat going through less air, we get more of it.

During the 2 equinoxes, the sun is in the same position in the sky.  You would, therefore, expect that the climate in March and September would be about the same.  Yet, we all know that it’s much warmer in September (about 74), than it is in March (about 45) (see chart).  As I’m writing this, a winter storm is dumping snow at my doorstep.  In September, we’re still planning outside barbecues and swimming in the lake.  Why then, is September so much warmer, than March?

The answer is that water is a poor conductor of heat, and the air, in this part of the world, is quite humid.  This humid air resists the heat of the sun, as it rises higher in the sky, from December to June.  But, the humidity also holds the heat in, as the sun gets lower from June, to December.  The phenomenon is called seasonal lag.  In the desert, where the air is dry, it’s very hot during the day, and freezing cold, at night, as any GI, who’se been to Iraq, can tell you.

So, time to put away the skis and get out the kayaks, as we enjoy the gradual return of the warm season, together, on Sunday afternoons.

Ever see a comet before?  You’ll have a chance, this week, to see a bright one, with a long tail  For 3 nights, Tuesday to Thursday, if any of those nights are clear, the waxing crescent moon will help you find it.  Go to a spot where you have a clear view of the western horizon, not later than 45 minutes after sunset.  On Tuesday, it will be close to a tiny sliver crescent moon.  On the next nights, the moon will be bigger and higher and the comet will be below it.  There’s lots of information about comets, in books and on the internet.

Overhead, and slightly to the west, is the constellation Orion, and the big planet, Jupiter.  On Sunday, Jupiter will be big and bright, and close to the moon.

The hemlock trees, Tsuga canadensis, in our forests, are threatened by an invasive insect, the hemlock wooly adelgid, Adelges tsugae.  Many old hemlocks grow on steep slopes, where logging wasn’t practical.  Loss of these trees would produce severe erosion of these hillsides, with many effects on ecosystems.  Migrating amphibians, already threatened by a fungus, would be threatened even more by losing the shelter and moisture they need.  In New York, many thousands of hemlocks have already been killed, in the southeast part of the state.  They have been found as far west as Yates County.

Springwater Trails hikers can help slow the spread of this killer by checking the hemlock trees we encounter, on our Sunday hikes, for the fluffy, white overwintering ovisacs on the leaves, from now, until the eggs hatch, usually around the end of April.  On this information sheet you can see what hemlock trees look like and what we’re looking for on them, as well as items that look like them.  Information sheets will also be passed out before the hike starts and ribbons to mark suspect trees.  Photographs will also be helpful.  The hemlock is one of the most common trees in this area and we’ve seen them on nearly every hike we do. There were many on the trail in Swain but, you’ll see why we can’t look for the ovisacs, when there’s snow on the trees.  Most of our hikes are west of where they’ve been found so, hopefully, we’re not going to find them.  If we do, Cornell Plantations will definitely want to know.  If you see a suspicious tree, mark it with your ribbon, take a picture if you can, and let Gene or Georgia know.  We will submit survey reports on every hike we take.  In case you’re motivated to do more, you can check into training classes, offered by Cornell Plantations in Ithaca, this month, where you will see actual HWA infestations, and participate in surveys in some beautiful areas of Tompkins County, in April.

We will also be looking for other invasive tree killers, this summer.  We will be presenting 2 programs for you to learn about them.  April 9, at the Springwater Historical Society meeting at the Springwater Town Hall, and April 10, at the Adirondack Mountain Club meeting at the Rochester Science Museum.