Sukkot

[cellio]

Tonight begins the week-long festival of Sukkot. (That's "booths", for those who were wondering what all the little huts springing up on lawns in Squirrel Hill are about.) Chag sameach to those who celebrate, and happy fall to everyone else.

Naturally, in a week when we're supposed to take our meals outdoors under the fragile roofs of these booths, it's slated to rain more than a little. :-)

(Oddly, according to my favorite weather site, the equinox is today. Isn't that rather late? Or should I automatically view with suspicion a site that tells me that there are "11:60" hours of daylight today?)

Comments

12 hours sunlight

[rob-of-unspace.livejournal.com]

There are several things that come into play.

One, the sun is bigger than the Earth. The sun "sees" past the halfway mark on the Earth, while we see less than 50% of the sun. Put a big circle next to a little circle: draw the line through the centers and the perpendicular lines to that line through the centers of the circles. Those two lines mark the "halfway." Now draw tangents to both circles -- there should be two of them. The smaller circle's tangents are beyond the halfway, while the larger circles tangents are before the halfway.

Two, the atmosphere refracts sunlight, so we get more than 50% daylight on the day when the sun is at it's highest point overhead.

Does that make sense to anyone but me?

Rob

Re: 12 hours sunlight

[cellio]

I'm not following the diagram, but atmospheric reflection sure makes sense, and I can grok the "the sun is big" idea even without the diagram. Thanks.