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Spring Starts Sunday, But Why Has the Date Changed?
SPACE.com ^ | posted: 18 March 2005 | By Joe Rao

Posted on 03/19/2005 7:08:25 PM PST by Puckster

In the years 2008 and 2012, those living in Alaska, Hawaii and the Pacific, Mountain and Central time zones will see spring begin even earlier: on March 19. And in 2016, it will start on March 19 for the entire United States.

There are a few reasons why seasonal dates can vary from year to year.

1. A year is not an even number of days and neither are the seasons. To try and achieve a value as close as possible to the exact length of the year, our Gregorian Calendar was constructed to give a close approximation to the tropical year which is the actual length of time it takes for the Earth to complete one orbit around the Sun. It eliminates leap days in century years not evenly divisible by 400, such 1700, 1800, and 2100, and millennium years that are divisible by 4,000, such as 8000 and 12000. 2. Another reason is that the Earth’s elliptical orbit is changing its orientation relative to the Sun (it skews), which causes the Earth’s axis to constantly point in a different direction, called precession. Since the seasons are defined as beginning at strict 90-degree intervals, these positional changes affect the time Earth reaches each 90-degree location in its orbit around the Sun. 3. The pull of gravity from the other planets also affects the location of the Earth in its orbit.

The current seasonal lengths for the Northern Hemisphere are:

Winter: 88.994 days

Spring: 92.758 days

Summer: 93.651 days

Autumn: 89.842 days

As you can see, the warm seasons, spring and summer, combined are 7.573 days longer than the colder seasons, fall and winter (good news for warm weather admirers).


TOPICS:
KEYWORDS: globalwarming; spring
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To: Puckster

This makes my head swim. It took me years to catch on to the "floating Easter" concept. Now I understand that Easter is on the first Sunday after the first full moon after the vernal equinox. I'm old. I get confused.


21 posted on 03/19/2005 9:11:12 PM PST by whereasandsoforth
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To: Puckster

Oh no--you mean the shrinking of the ozone hole at the poles is a naturally occurring event?

Time to crank up the air conditioners then!!


22 posted on 03/19/2005 9:36:24 PM PST by exit82 (You see, I've been to the desert on a horse with no name--then I found FreeRepublic.)
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Comment #23 Removed by Moderator

To: Puckster

March 21 always, isn't it?


24 posted on 03/19/2005 10:29:39 PM PST by Salvation (†With God all things are possible.†)
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To: Puckster
All that is true, as well as Mt. Erebus as a source of the Cl and Br.

But, also remember that diatomic oxygen absorbs the highest-energy ultraviolet radiation from the sun, namely, all radiation with wavelengths shorter than 240 nm. However, there is a great deal of ultraviolet radiation between 240 nm and 290 nm that is not absorbed by O2 molecules. This radiation is absorbed by ozone.

The ozone in the stratosphere is produced by photochemical reactions involving O2. When diatomic oxygen in the stratosphere absorbs ultraviolet radiation with wavelengths less than 240 nm, it breaks apart into two monotonic oxygen atoms.

The resulting oxygen atoms combine with O2 molecules to form ozone.

O(g) + O2(g)=>>O3(g)

This reaction is exothermic, and the net effect of the previous two reactions is the conversion of three molecules of O2 to two molecules of ozone with the simultaneous conversion of light energy to heat. Ozone absorbs ultraviolet radiation with wavelengths as long as 290 nm. This radiation causes the ozone to decompose into O2 molecules and oxygen atoms.

This, too, is an exothermic reaction. The overall effect of this reaction and the previous reaction is the conversion of light energy into heat. Thus, ozone in the stratosphere prevents highly energetic radiation from reaching the Earth's surface and converts the energy of this radiation to heat, and as long as there is oxygen(O2) and sunlight you will have ozone(O3) in short order.

The Freon ban used ozone destruction as a scaretactic. It wasn't about ozone as much as it's about greenpeace's war on chlorine, technology, and man.

25 posted on 03/19/2005 10:31:32 PM PST by PeaceBeWithYou (De Oppresso Liber! (50 million and counting in Afganistan and Iraq))
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Comment #26 Removed by Moderator

To: Puckster; RadioAstronomer
Longer warm seasons in the Northern Hemisphere correspond to longer cold seasons in the Southern half. Which seems to be consistent with:

"Further evidence that the Antarctic as a whole is in the midst of a cooling trend comes from the study of Watkins and Simmonds (2000), who analyzed region-wide changes in sea ice. Reporting on trends in a number of Southern Ocean sea ice parameters over the period 1987 to 1996, they found statistically significant increases in sea ice area and total sea ice extent, as well as an increase in sea ice season length since the 1990s. Combining these results with those from a previous study revealed these trends to be consistent back to at least 1978. And in another study of Antarctic sea ice extent, Yuan and Martinson (2000) report that the net trend in the mean Antarctic ice edge over the last 18 years has been an equatorward expansion of 0.011 degree of latitude per year. "

From:
New Antarctic study disputes CO2 Global warming link

Milankovitch theorized some effects of precession on climate. The summaries I have seen of his work emphasize solar angle and proximity. Do you know if he took the variation in the length of the warm seasons into account?
27 posted on 03/19/2005 11:03:43 PM PST by Ragnar54
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To: Puckster; abbi_normal_2; Ace2U; adam_az; Alamo-Girl; Alas; alfons; alphadog; AMDG&BVMH; amom; ...
Rights, farms, environment ping.
Let me know if you wish to be added or removed from this list.
I don't get offended if you want to be removed.
28 posted on 03/21/2005 11:59:38 PM PST by farmfriend ( Why oh why didn't I take the blue pill?!?)
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To: Ragnar54

Winter: 88.994 days

Spring: 92.758 days

Summer: 93.651 days

Autumn: 89.842 days


I'm not sure what all this stuff about "models" and CO2 and O2 and all that other scientifical stuff has to do with global warming. It's 'cuz are summers are longer than our winters.


29 posted on 03/22/2005 12:07:55 AM PST by geopyg ("It's not that liberals don't know much, it's just that what they know just ain't so." (~ R. Reagan))
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To: whereasandsoforth
Now I understand that Easter is on the first Sunday after the first full moon after the vernal equinox.

There are many people who seem to think it's the first Sunday after Christmas. :=)

30 posted on 03/22/2005 12:11:24 AM PST by Bob
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To: farmfriend

BTT!!!!!!


31 posted on 03/22/2005 3:08:06 AM PST by E.G.C.
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To: Bob
Oh! (gasp) It's YOU, bob!!!

(remember the old commercials with that great theme?)

32 posted on 03/22/2005 7:46:06 AM PST by SierraWasp (GovernMental EnvironMental Parasitic Pissants perpetually tormenting America Progress!!!)
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To: farmfriend
Why you pingin me to a two or three day old thred??? Especially one about dates on the calendar??? You had me all cornfused!!!

Interesting thred, just phunny how easily it can mix up an imprecise soul as the Waspman...

33 posted on 03/22/2005 7:56:53 AM PST by SierraWasp (GovernMental EnvironMental Parasitic Pissants perpetually tormenting America Progress!!!)
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To: infidel44
I thought that gravitational attraction between two bodies was dependant on their masses, and of course distance,

 Yes, this is true.

But...

1) The speed of an object is changed when it is moving at other than right angles to the line between it and the other object.

2) The Earth is not a single object. The oceans move with respect to the land.

3) The Moon causes a tidal bulge on the Earth's oceans.

4) But the tidal bulges produced on Earth by the Moon are not centered at the point on Earth's surface directly below the Moon, but are shifted ahead of the Moon because of Earth's faster spin rate.

The net result is that the center of mass of the Earth is always slightly ahead of the Moon and so it is constantly increasing the Moon's speed. And the Earth's rotation is slowed.

34 posted on 03/22/2005 9:48:45 AM PST by Dan Evans
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To: Puckster

It's George Bush's fault.


35 posted on 03/22/2005 10:13:28 AM PST by Blood of Tyrants (G-d is not a Republican. But Satan is definitely a Democrat.)
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To: SierraWasp
Why you pingin me to a two or three day old thred???

I had nothing to do!!!

36 posted on 03/22/2005 10:30:34 AM PST by farmfriend ( Why oh why didn't I take the blue pill?!?)
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To: farmfriend

Well after bein back in the nations Crapitol, yer bored, right?


37 posted on 03/22/2005 10:44:40 AM PST by SierraWasp (GovernMental EnvironMental Parasitic Pissants perpetually tormenting America Progress!!!)
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To: SierraWasp
Well after bein back in the nations Crapitol, yer bored, right?

No just a little tired of all terri all the time.

38 posted on 03/22/2005 11:07:31 AM PST by farmfriend ( Why oh why didn't I take the blue pill?!?)
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To: Puckster

I am going to Alaska to see the glaciers this September, I sure hope they don't melt before I get there.


39 posted on 03/22/2005 11:20:50 AM PST by razorback-bert (FR's spell checker thinks Freepers isn't a word)
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To: farmfriend

Well, I'm gonna post Schwarzenegger's big swipe at seniors using MediCal's benefits in place of buying Long Term Care insurance. That oughta break up the monotony...


40 posted on 03/22/2005 11:28:35 AM PST by SierraWasp (GovernMental EnvironMental Parasitic Pissants perpetually tormenting America Progress!!!)
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