My nephew claims that Summer 2004 will be five days longer [than last summer (I assume)]. I don’t know where he heard or read this. He couldn’t defend this statement other than the fact that the earth will be furthest from the sun on July 5th…but I fail to see the relevancy. Isn’t there some way to show that all seasons are about the same in length? Maybe I could use Kepler’s laws of planetary motion, or something? Any thoughts how to disprove his statement? (Or, maybe a SDoper can prove him right???) - Jinx
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First of all, you can impress your nephew by pointing out how the soltices/equinoxes have nothing to do with the start/end of seasons. Officially, in the US, the NWS uses Dec-Jan-Feb as “winter”, etc. Other countries use other dates.
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The Earth closest approach to The Sun is in early Jan. This is when the Earth is also moving fastest. This means the time from fall equinox to vernal equinox is shorter than vice versa.
Checking online I get for 2004:
Summer solstice: 20:57 EDT 6/20
Fall equinox: 12:30 EDT 9/22
Winter solstice: 7:42 EST 12/21.
My mental math gives about 2 days more for the period from equinox to winter solstice than from summer solstice to equinox.
This gets a little tricky. Seasons are by tradition considered to be segments of the year as divided by the solstices and equinoxes.
The temperate zones (and frigid zones too, for that matter) experience sunlight seasons based on the solstices. Around the “summer solstice” in the Northern Hemisphere both solar intensity and length of day are at maximum, and thus there is maximum temperature affect on the weather. Because of what is called seasonal lag the actual observed affect on daily temperatures takes about one-eighth of a year to be made manifest. But one eighth of a year is the length of half a season! So from a weather standpoint it makes sense to consider Northern summer to last from June 21 to September 22 or 23. All this time the sunlight for N.H. is declining.
At opposite, December 21-22 should be a turning point in winter before it temperature should be in decline, but after it temperatures should steadily rise. Again, because of seasonal lag, Old Man Winter is considered to be just starting.
The reverse is true in the Southern Hemisphere, of course.
But the traditional division is not used by everyone. Here in the U.S. meteorologlists like to group months together, so that no seasonal change “occurs” during a month. I’ve heard that in England Winter is actually November, December and January, making February the first month of Spring! I can only surmise that this system is due to the greater latitude (enhancing the daylight effect) and the warm ocean current (minimizing the significance of actual temperature change).
(Nor are these three the only ideas people have about the breakdown. Cecil recently had a column about when the warmest N.H. Summer days actually occur, on the average. I’ll provide a link if I can dig it up.)
Seasons by the traditional breaks would definitely be about the same length. This is because the earth’s orbit has low eccentricity. However the perihelion (minimum distance) is about the same time as the N.H. Winter Solstice. Since the earth has a shorter distance to go and a greater space velocity vector(speed) we would expect Spring and Summer to be the long seasons and Fall and Winter the short ones, and this is so. * In fact, if the perihelion were exactly at the N.H. Winter Solstice the first two would be exactly the same length, and the second two would also match. In fact Winter is marginally the shortest season, something we in the N.H. are grateful for. Summer, of course is the longest.
By month grouping the season lengths would of course be determined by month lengths, which are a bit arbitrary.
So, to answer your question, the length of summer is bound to be about the same length it was last year by the traditional method, and exactly the same by either month-grouping method (February being the only varible). And the traditional length of Summeris nowhere near an excess of 5 days, even over Winter.
So your nephew probably misunderstood what he had heard.
True Blue Jack
- This is according to Kepler’s Law, so, yes, you could say that Kepler’s Law is in opposition to your nephew’s statement - in conjuction with the fact of earth’s low eccentricity.
Wasn’t there a Country Time Lemonade commercial that stated something to that effect?!
Remember I promised a column citation?
Cecil speaks:
In North Dakota and Canada, if summer comes on a weekend everyone goes on a picnic.
Well, Frankie Valli is quite short compared to the other three.
Whut?
Oh, those seasons!
Carry on.
I think most people are answering a question which was not asked and are not answering the question which was asked.
The way I understand it the OP asks if the summer of 2004 will be 5 days longer than the Summer of 2003. The answer is NO. while the different seasons are not of the same duration, one summer (from equinox to solstice) lasts the same as any other summer.
True Blue Jack
Sounds to me that True Blue Jack answered the question true blue.
I assumed that Jinx’s “I assume” meant that we were free to try to make better sense of the claim than he did. The eccentricity of orbit is basically the only thing that makes sense here.
Checking my math: I now get 4 days difference, not 2. Close enough to the 5 day claim that the nephew is starting to sound sensible. Esp. if one were to compare “summer” to “winter” instead of “fall”. (Again there’s that seasons relating to solstice/equinox nonsense. Which is not traditional, as per Cecil’s column.)
Thank you , barbitu8!
True Blue Jack