Tuesday, February 23, 2010

Come on Spring!

I was thinking a lot about Spring today, as the last warm day for a little while is on my doorstep.  Is there anybody out there who isn't ready for Spring? Okay, besides the southern-hemispherians?
"I'm Ready"

Then I was musing (totally off topic again)... what really makes spring come anyhow?  What makes Spring spring?   Why won't it get here already?!!! Some of you from Pennsylvania will tell me it has to do with a groundhog, and some who remember 6th grade reasonably well will say it has to do with our rotation around the sun.  And there are those who might add Spring happens because the days get longer, allowing the sun to heat us up a little more.   All of these are sort of correct (well, maybe not the Phil thing), but then again, not exactly.   The Earth could rotate until it spun off its axis and it wouldn't change the temperature without one key ingredient.  The days wouldn't get longer or shorter save for this ingredient either.   And despite popular myth it is NOT correct that the seasons change because we are closer to the sun.

It is, of course, the tilt of the earth.  The fact that we spin on our own axis cocked sideways in comparison to our orbit around the sun (the "orbital plane" in Scientific American speak) is what creates the seasons.  Without that tilt, everyone would have a temperature and daylight very similar to everyone else, making room for differences in altitude and weather patterns.  How crazy and random is that when you think about it?  And think about what it would mean if we shifted our tilt? Talk about climate change, and melting polar icecaps!    Some more food for thought, the tilt is changing!  It varies every 41,000 years or so by about 2.5 degrees.

Okay, getting off track here in my thinking out loud.   Here's a picture to illustrate from Wikipedia:
"The North Is Getting Shafted"

So, the orbital tilt.. exactly what does it change that causes these seasons?   First, as is probably obvious, the tilt causes one side, either north or south, to have significantly less sunlight then the other side as we rotate daily along the equator.  When it comes to the poles, we are talking TOTALLY less light.  More light, means more sun baked radiation, which means more warmth (and more skin cancer).    The other major contributing factor though is the obliquity of the sun to the spot you are standing.  On the 'far side' (i.e. winter), the larger angle of obliquity (less directness) translates also into less radiation for the light we do get.  That's why summer sun seems stronger than winter sun, and Florida sun seems hotter than Maine sun.  Because it is. This is also why there is ice at the poles even in Summer.  The sun is always oblique to a large degree at the poles.

Well, I'm glad I got that all cleared up :).   I could go on about solar altitude and radiation lag.. but this is already nerdy enough, and way totally off topic again.

And really this is all to say, of course:  Hurry up Earth, I'm sick to death of the dark side!  Give it back to Australia and Argentina already.

12 comments:

  1. Jess, I love it when you give us science lessons. One year around this time, a group of faculty members at the Maine college where I taught were talking about how there's hardly any spring in Maine, it just kind of goes from winter to summer with a couple of weeks of mud in between. A faculty member who was originally from South Carolina begged to differ. He said, "Spring here lasts for months, but there's never any summer." -Jean

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  2. Hi Jess, never mind if it's off topic, many people will learn from that bit of lecture. I am in science so i know that, but i am really fascinated and still amazed how people near the poles feel, especially the 6 months night and 6 months day! For me it is exciting to have the sun still at 4pm position even if it's already 10pm!

    By the way, about the question of the name of the green Cattleya, i am so sorry as i dont remember their names. I just know they are Cattleya, so you are safe if we will say Cattleya sp. hehe. thanks for looking at my older posts.

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  3. Jean - lol. I think he's got you there.

    Andrea - Thanks for the visit, I hope you come back! I'm going to find one of those Orchids. There is a nursery here that has quite a few and I bet if they don't have it they could get me one.

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  4. adorable statue! i could see those pots filled with sedum dripping out.... or violets.

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  5. I'm sitting here reading this over my morning coffee, and I think my brain just about exploded lol. Love the science!

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  6. Jess - thanks for visiting my blog (you'd love Monet's Gardens).

    This winter thing is getting old, isn't it? Good science here.

    Cameron

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  7. Kyna - Science-y stuff and coffee don't mix well huh?
    Cameron - So old, so old. It is going to freeze tonight. The tulip trees are all going to turn into brown tissuey messes. If it never gets winter again it will be too soon.

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  8. Dame right, don't day get enough sun down there in OZ anyway. The only thin missing from your diagram is the big rain cloud that is parked over Ireland for 360 days of the year, here we just notice the rain get a little warmer in the summer.

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  9. Ha! Speaking as a Southern Hemispherian, you can have that hot old sun for a bit. I'm over him and his earth baking, nose burning ways :D

    Great post and I really don't think that it's off topic at all!

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  10. Great post - I've printed it out and stuck it on my noticeboard.

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  11. Stone Art - I stand corrected, all future maps on my blog will include a rain cloud over Ireland. ;)
    Gipps - My friend from Perth says the same thing, and I was saying the same thing last August, but none of us knows what we were talking about!
    Sue - Thanks, that is an honor!

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