For those who like their quiet, to enjoy the pure sounds of nature, the period from mid-April to early May sure is a nice time of year. The snowblowers and snowmobiles are retired for the season, while the lawnmowers have yet to make their appearance. And it is at this very time of year that the birds all start singing their hearts out.
In April and early May, when you’re outside enjoying the birdsong, if it’s sunny and pleasantly cool, you must always remember that it’s the sun angle, not the temperature, that will burn you. Every year, folks get surprise April sunburns, because they go by how cool the air feels. Today’s Star Herald comes out on May 2. The date that the sun has the same solar intensity as May 2 is Aug. 9. A good way to visualize that every date has a “cousin” with the same solar intensity, is to visualize the low-to-the-horizon winter sun getting higher in the sky.
ESN stands for elevation (of the sun) at solar noon, which is defined as the highest the sun gets in the sky on a given day. From the sun’s lowest point above the southern horizon at noon on the winter solstice, to its highest point above the southern horizon at noon on the summer solstice, takes about half a year (Dec. 21 to June 21).
To better understand that each date prior to the summer solstice has a cousin on the other side of the summer solstice, just picture the fact that the sun, on its way back down to its lowest point, following the summer solstice, is going to pass through all of the same elevations above the horizon at solar noon each day as it did when it climbed in the sky after the winter solstice. So how did I know that May 2’s “cousin” was Aug. 9? Well, May 2 is 19 days and a month before the summer solstice, and Aug. 9 is 19 days and 1 month after it.
Switching gears, now that things have finally started warming up, people are thinking about getting their gardens going, and at the same time, they are thinking about whether they are out of the woods with respect to frost danger.
When considering frost, I like to use 36 degrees, rather than 32 degrees, for the following reason: temperature is officially measured at 5 feet above the ground. However, on a clear. calm night, the temperature can be several degrees cooler right on the surface of the ground. This explains why you can sometimes have a forecast low in the mid-30s, while having frost in the forecast.
So for Caribou, the average date for the last 36-degree overnight low in spring is May 2, while the average date for the first 36-degree overnight low in fall is Oct 10.
I’d like to close this column by acknowledging my father, who would have been 100 years old this month. He would have been pleased to see me pursuing my passion for weather. Unfortunately, he passed before I started my career.
However, in a bit of serendipity, this happens to be my 100th column, published in the same month (May) when he would have been 100 years old.
Now that’s pretty cool.
Ted Shapiro holds the Broadcast Seal of Approval from both the American Meteorological Society and the National Weather Association. An Alexandria, Va. native, he has been chief meteorologist at WAGM-TV since 2006. Email him at tshapiro@wagmtv.com.
