Hello, summer! Solstice arrives Saturday evening
Summer moves into Maine at 5:43 p.m., Saturday, June 20, and the weather couldn’t be more summerlike. The celestial action continues this Solstice with a rare solar eclipse, although it won’t be visible to the naked eye in this part of the world.
Living at latitude 44.18, we have the short bittersweet days of winter, when light compresses into a mere seven or eight hours. But then we are graced with beautiful and languorous days of late spring and early summer, when skies begin glowing before 4 a.m. and don’t fully darken until 10 p.m.
Who could ask for more!
Summer 2020 will be 93 days, 15 hrs, 46 minutes in length.
On June 20, the sun will reach its northernmost point in the sky, +23.5 degrees above the celestial equator. This marks the moment when it feels like we are nearest the sun, before we start rotating the other way. You know. Toward winter.
But that is a long way off. Saturday morning there will be patchy fog and then it will be sunny, meteorologists say, with a high near 84 degrees F and a light southerly breeze. No major storms are on the immediate horizon, so it makes a good time to get out and celebrate summer’s arrival, maybe weed the garden.
What good is the warmth of summer, without the cold of winter to give it sweetness.
~John Steinbeck
Sumer is icumen in,
Lhude sing, cuccu;
Groweth sed
and bloweth med,
And springth the wode nu;
Sing, cuccu!
— A Middle English song, probably written by John of Fornsete, in 1226, according to Notes on the Songs.
Sunrise is at 4:55 a.m. and sunset is at 8:26 p.m.
From NOAA:
The summer solstice occurs at the moment the earth's tilt toward from the sun is at a maximum. Therefore, on the day of the summer solstice, the sun appears at its highest elevation with a noontime position that changes very little for several days before and after the summer solstice.
The summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° latitude North, and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China. For every place north of the Tropic of Cancer, the sun is at its highest point in the sky and this is the longest day of the year.
The winter solstice marks the shortest day and longest night of the year. In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa.
From the U.S. Naval Observatory:
We have all been taught that the seasons are caused by the 23.4° angular offset between the Earth's axis of rotation and the perpendicular to the Earth's orbital plane with the Sun (see obliquity below). The Earth's rotational axis stays nearly fixed in space, even as the Earth orbits the Sun once each year. As a result, when the Earth is at a certain place in its orbit, the northern hemisphere is tilted toward the Sun and experiences summer. Six months later, when the Earth is on the opposite side of the Sun, the northern hemisphere is tilted away from the Sun and experiences winter. The seasons are, of course, reversed for the southern hemisphere.
The solstices mark the two dates during the year on which the Earth's position in its orbit is such that its axis of rotation is most tilted toward or away from the sun. These are the dates when the days are longest for the hemisphere tilted toward the Sun (where it is summer) and shortest for the opposite hemisphere (where it is winter).
However, there is a complication. The Earth's orbit is very close to being a perfect circle, but not quite. It is somewhat elliptical, which means that the distance between the Earth and the Sun varies over the course of the year. This effect is too weak tocause the seasons, but it might have some influence over their severity. The remainder of this page explains this possibility.
The Earth reaches perihelion - the point in its orbit closest to the Sun - in early January, only about two weeks after the December solstice. Thus winter begins in the northern hemisphere at about the time that the Earth is nearest the Sun. Is this important? Is there a reason why the times of solstice and perihelion are so close? It turns out that the proximity of the two dates is a coincidence of the particular century we live in. The date of perihelion does not remain fixed, but, over very long periods of time, slowly regresses (moves later) within the year. There is some evidence that this long-term change in the date of perihelion influences the Earth's climate.
For the Northern Hemisphere, the Winter Solstice is the shortest day of the year. In the steady march of the year in the Arctic, the days gradually grow shorter between June and December until the far North plunges into the complete darkness of winter. The trend reverses at Winter Solstice, the point during the year when the Northern Hemisphere is the most inclined away from the Sun. After the solstice, which falls on December 21 or 22 every year, the days begin to lengthen. Probably because the day marks the beginning of the return of the Sun, many cultures celebrate a holiday near Winter Solstice, including Christmas, Hanukkah, and Kwanzaa.
On Winter Solstice, the polar North receives no energy from the Sun. In contrast, the amount of incoming solar energy the Earth receives on June 21, Summer Solstice, is 30 percent higher at the North Pole than at the Equator. The contrast between Winter and Summer Solstice is illustrated in these images. The images show the amount of sunlight that is reflected from the Earth as measured by theCERES instrument on NASA’s Terra satellite. In the top image, taken on Winter Solstice 2004, the far North is dark blue, indicating that no sunlight is being reflected back into space. The most sunlight is being reflected out of the Southern Hemisphere, where December 22 marked the longest day of the year. The lower image shows Summer Solstice 2005. Darkness dominates the South, while the North is now the location receiving and reflecting the most light. In both images, bright white clouds stand out because they are reflecting so much light back into space.
Notice how the polar North reflects less light during its summer (June) than the polar South reflects during its summer (December). The reason behind this is land cover. Antarctica in the south is nearly entirely covered with bright white snow, which reflects light well. The northern oceans are also capped with sea ice, but the area covered with sea ice during the summer has declined in recent years. Snow cover has also decreased on land. According to a study published in Science on October 28, 2005, snow in the Arctic melted on average two and a half days sooner per decade between 1961 and 2004. Open water and snow-free land both absorb more sunlight than reflective ice, and they warm the atmosphere as they release the absorbed heat. Heat in the Arctic increased by about 3 Watts per square meter per decade between 1961 and 2004, the same amount of heating that climate change models predict after several decades of greenhouse gas warming. The Arctic is now warmer than at any time in the past 400 years, and the warming trend is likely to continue. Warmer temperatures and thawing soil will allow shrubs and trees to move farther north, and they absorb even more energy than the tundra that currently covers the North.
The Sun's track across the sky is much shorter and lower in the winter than in the summer. During the early fall, as the Sun moves lower in the southern sky, sunrises get later, and sunsets earlier.
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