Archive for the ‘Seven Sisters’ tag
This image from my recent ride along the Bolinas Ridge captures the specific time of the evening — civil twilight — when ambient light takes on a lovely bluish hue prized by painters and photographers.
But twilight (both morning and evening) is divided, more scientifically, into civil, nautical, and astronomical segments based upon the number of degrees the center of the sun is below the horizon (6, 6-to-12, and 12-to-18 degrees respectively).
Evening nautical twilight (nautical dusk) is said to end once sea navigation via the horizon line is no longer possible. Evening astronomical twilight (astronomical dusk) ends once the dimmest celestial objects (e.g. galaxies and nebulae) become properly visible to astronomical observation.
Commentary: in the context of the virtual world of Texting, Tweeting, and Tagging (from which I claim no exception) it feels palpably iconoclastic (if not downright subversive) to patiently witness our solar system’s sun disappearing ever so gently beyond the planet’s watery horizon.
Featured Comment by Shoeless Joe: “There is a biological connection, too, as the rods and cones in our eyes perceive light differently at twilight. It is called the Purkinje Shift (or Purkinje Effect). Wikipedia has a good article on it. One of the beauties of cycling is that it affords many opportunities to “patiently witness” the world around us in a way that is unique to the sport.”
Bay Area on 12/05/09! Got to love the sunshine. And what a picture postcard vista.
You too can find the spot by clicking on the map link under the photo.
In the background are a few of the storied “seven sisters” — a series of beautiful rolling hills. Some are actually quite steep and not so rolling (see also here and here for a few more images of this stretch). I tend to get distracted by the scenery and want to get off my bike and have a little wine, cheese, dried fruit, or whatever else I’ve stowed in my big, roomy front handlebar bag!
12/05/09: Current and former New York City Bicycle Club members Tania, John, and Carmen. Tania was in town for a visit. John and Carmen now live in SF. I did my best to keep up with these fast club riders during a very hilly 35-40 mile loop to and from Fairfax via Panoramic Highway and Mill Valley. (Here’s a map of the route.)
Riding toward the summit of Mt. Tam, I struggled to maintain momentum over the series of seven undulating hills, known as “The Seven Sisters” (scroll down to the bottom of this page for more details on the sisters).
Apparently, 90% of all North American car commercials are filmed along this stretch of roadway. I’ve only seen filming once twice.