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).
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.
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!!
March 21 always, isn't it?
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.
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.
There are many people who seem to think it's the first Sunday after Christmas. :=)
BTT!!!!!!
(remember the old commercials with that great theme?)
Interesting thred, just phunny how easily it can mix up an imprecise soul as the Waspman...
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.
It's George Bush's fault.
I had nothing to do!!!
Well after bein back in the nations Crapitol, yer bored, right?
No just a little tired of all terri all the time.
I am going to Alaska to see the glaciers this September, I sure hope they don't melt before I get there.
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...
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.