At this site: Sun & moon times today, Montréal, Quebec, Canada, which gives the length of day in Montreal for the next week a footnote on the table says, "December solstice (winter solstice) is on Saturday, December 21, 2013 at 12:11 PM in Montreal. In most locations north of Equator, the shortest day of the year is around this date. “Most locations”?, “Around this date”? What’s going on here? I would have assumed that 12:11 PM EST (or 17:11 UMT) was the time that the earth presented maximum tilt to the sun and that it would be the shortest day everywhere that had any day at all and would be exactly on this date (or the next, if your time zone is +7 or higher). What am I missing here?
I assume they are using the weasel words to exclude areas like Barrow, Alaska that don’t see the sun for months on end during the winter. Their shortest day is the last day that the sun peeks up over the horizon (or the first day in Spring when it does the same).
I’m sure if you went to just the right spot you could find a place where their shortest days were Dec 20 and 22 with no sunrise at all on the 21st.
Also, since the maximum tilt angle doesn’t occur at exactly midday on the 21st for Greenwich Mean Time it will be one day earlier or later for small parts of the globe.
Wouldn’t mountains on the horizon affect day lengths and the precise point of “shortest day”?
With regard to “around this date”, I think you answered your own question with your final parenthetical.
Finally, I went to a number of different locations and it was always at a time that was 17:11 GMT on Dec. 21. So “around” should have been “today or tomorrow, depending on time zone”. Next winter it ought to be displaced by nearly 6 hours, so it ought to be Dec. 22 in Greenwich, but still Dec. 21 here. By the same reasoning, it ought to be within a couple of minutes of midnight here in 2015. After I think, since the length of the year is only 1 1/4 minutes short of 365.25 days. Of course, in CST, it will still be on Dec. 21.
No. Mountains will affect the amount of light in a given area, but the sun’s place on the (theoretical) horizon isn’t dependent upon local geology.
But then you have to ask, when people talk about the “shortest day”, do they mean the theoretical day based on the Sun’s location relative to the theoretical horizon, or do they mean when it’s light out?
If the latter, you can get further complications from atmospheric refraction, which adds a few minutes to the day length, and which can vary a bit based on temperature and pressure.
So which do you mean?
December 21st is the shortest day of the year - only 23 hours long. It comes out of the daylight hours. June 21st is the longest day - 25 hours, so it averages out to 24 around the year. “Daylight Savings time” is what is used to put the hour of daylight time back in.
My Uncle Red Green is “Honest as the day is long.” That’s why he’s least honest on December 21st.
This is all wrong. Haven’t you ever noticed that Daylight savings has always begun in March or April, and ended in October or November? Nothing to do with the Summer or Winter solstice.
Well I am with the OP, the quote got it wrong.
There mistake was to use of two approximation qualifiers…
They said “Most places have the solstice around this date”, which implied some areas have the
solstice a long way from this date. No.
Or perhaps they meant that ± one day error was more than "around this date " allowed ?
No. Surely an error of ± one day is the smallest error that “around this date” allows… the error we are talking about is the smallest error that dates can have, so it must be that “around this date” applies.
Or for further clarity, here’s what each of approximation refers to…
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“Most places” (not all ?) What is the most accurate thing we can say about “Most places” ( of the Northern Hemisphere and excluding the arctic areas) … Most places have winter solstice on this ONE date. (some have it the next day , or the day before.)
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What is the most accurate thing we can say about which places have solstice “around this date” ? ALL places (that have solstices.) have the solstice around this date. (no place has it one week different… )
And they already said that most of the Arctic area is excluded from this, because its not getting ANY daylight at this time of year …
Southern hemispheres summer solstice may not be the same date as the northern hemisphere’s winter solstice, but its surely the day before or after if its not the same date.
One pleasant side effect of this phenomenon is that summer is about 4% longer than winter.
I tried that thing about spinning an egg around on the Solstice but it didn’t stand on end when I did so. I was confused, but then I often am.
Therefore, I am blaming the Farmer’s Almanac because I am pretty sure that is where I first read about this.
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What you are looking for is called an ephemeris.
There are many resources online for this, including the aforementioned Farmer’s Almanac.
I hope your whole post is a joke, and this is the punch line.
If you’re serious, try testing your hypothesis. Use a stopwatch to time the interval between two successive sunrises or sunsets, around the times of the solstices. You’ll find that both are very close to 24 hours.
The discussion regarding solstices and “length of the day” are about the length of the daylight hours (between sunrise and sunset) not between two successive sunrises or sunsets. I mean, think about it: the Earth is spinning like a top. Why would it spin slower in the summer and faster in the winter (in the North Hemisphere, while doing the opposite in the South, and midway between the two on the Equator)? It would take a pretty flexible globe!
Although winter solstice is the shortest day (mol), the sun continues to rise later for about 3 more weeks. The sun begins to rise earlier on 1/10 or 1/11. Here in Charleston, the latest it rises is 7:23 or 7:24, and begins to slowly rise earlier on 1/10 or 1/11. It sets later, too, making the net day longer. It actually began to set later before the solstice: http://www.accuweather.com/en/weather-blogs/astronomy/strange-phenomena-with-sunrise-and-sunset-this-time-of-year-1/58871