Tuesday, December 9, 2008

Dark Days in the Northern Hemisphere

OK, this post goes out to all of you Northern Hemisphere dwellers who are affected by Seasonal Affective Disorder, or the winter blues, or who are just bummed out by finishing the day's work when it's already dark outside.


For tonight's sunset -- Wednesday's, that is -- will be the earliest of the year. If tomorrow, as you leave your office or classroom or factory or whatever it may be, or as you glance up after a long day of righteous labor in the home, if it seems just a tiny bit brighter than it was today -- that's 'cause it is.

But isn't the solstice still eleven days away?

Yes, it is. But the solstice, although it is the shortest day of the year, does not have the earliest sunset or the latest sunrise. The earliest sunset comes today, and then starts creeping later. By the 21st, the sunset is getting later exactly as fast as the sunrise is getting later, and thereafter starts to outpace it. By about January 3rd, the sunrise starts creeping earlier too, and before you know it it's spring.

But Why?

It's really hard to explain. It has to do with the fact that the Earth moves faster through the arc of its orbit this time of year, when it's closer to the sun, giving the cycle of day and night a little push forward. The pattern is reversed in June and July, when we are the furthest from the sun.

Can You Elaborate?

No. I can barely keep it straight in my own head, let alone articulate it clearly. You'll just have to roll with it.

[Photo taken via Google image from the Flickr site of someone named Alice Thelma, who presumably owns the copyright. I imagine it's the same Alice Thelma who has this blog of phenomenal Portland-at-night photos.]
Wednesday Weigh-In: 205 lbs, 2 below plan, not necessarily for great reasons but I'll take it.


Anonymous said...

Hallelujah. Daylight savings is just around the corner!!!

RYC: Is the "Ew..." in reference to something I said? Or to the Whole Foods Craptastity?

(PS, currently, "craptastity" returns 40 hits on Google. Hellloooo 41!)

Jenners said...

Oooooohhh...should you credit people for photos when you steal them off the Internet? Hmmmmmm. I've been very very guilty. They shouldn't make it so easy...

Thanks for the update...I do hate the early darkness...makes me tired.

DrSchnell said...

I just discovered this oddity last year (of latest/earliest sunset/sunrise not coinciding with the solstice) for the first time. I have yet to convince many people that it is actually true, so I thank you for your corroboration. Next time somebody says "nuh-uh!!" I'll just say - "yeah, well I got it straight from the M5K!" and they'll say "huh?" and I'll say "yeah!" and they'll just walk away confused.

Michael5000 said...

@MyDog: "Hallelujah" = good rejoicing!

@Jenners: You should always credit easily identifiable photos stolen off of the internet from parties who may end up noticing what you've done (because, for instance, you are posting a link back to their site). Technically, of course, you shouldn't steal photos off the internet. Because it's very very bad.

@DrSchnell: Another way to convince them it is true would be to refer them to a table of sunrises and sunsets. Consulting these charts is a bit of an obsession for me this time of year, is how I figured it out.

Karin said...

(you're) Always Look(ing) on the Bright Side of Life!

MulchMaid said...

Thank God!

jovaliquilts said...

Thanks for adding to the info I already don't understand about the solstice. I know (or I was told by someone who knows) that the longest day of the year is often the day after the summer solstice because of something to do with the refraction of light and the curve of the earth. Now I 'know' this other thing, except I don't think I could repeat it correctly.