04 September 2015

Change of the Season

Late Summer is a time when the heat waves set in, giving everyone a last taste of the warmth that longer days and warming landscapes bring. However, as Earth approaches the Autumnal Equinox, the days are becoming noticeably shorter as sunrises arrive later in the morning while sunsets arrive earlier in the evening. The dual effect is most pronounced around the time of the Equinox, as the amount of time the Sun spends above the horizon shrinks most rapidly in this period.

Change of the Season
Every day throughout the year, the time of sunrise or sunset changes slightly, extending the number of hours of sunlight from December until June, and reversing course from July until December again. However, the mid-points of this gradual change are the Equinoxes, the point at which the change is at its greatest (tip for the mathematically inclined: it is the maximum point of the first derivative of the duration of the day, a sine wave that is passing through an intercept J).

What does this feel like? Take note of this for the coming weeks as you experience your daily routine, and notice the time when brightness arrives in you morning and when darkness sets in each evening. The change is quite pronounced, with the amount of daylight diminishing by up to 30 minutes in a single week in mid-September, at mid-northern latitudes as we have in San Francisco. If you are located further north in latitude (Canada, Northern Europe) the effect is even more pronounced, with up to an hour in a single week! I find this fascinating and marvel every year at the dramatic changes that we all take for granted in our environment. Fall is indeed a season of great change. Savor the moments.

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