Just about all of these kinds of questions have their answer in the speed of the Earth in its orbit, and the observer's latitude, during the relevant time of the year. The Sun appears to travel faster in the sky when the Earth is whipping around the Sun near its perihelion period in December. It moves more sluggishly during its aphelion period in June. During a one day period near perihelion, the Sun's 'sky velocity' changes appreciably between sunrise and sunset. The result is reflected in the specific sunrise and sunset times by several minutes. Consider the following examples at various latitudes on the Earth:
Date Sunrise Sunset Daylight hours
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Latitude=0
December 4 5:47 17:54 12:07
8 5:48 17:56 12:08
12 5:50 17:58 12:08
16 5:52 18:00 12:08
20 5:54 18:02 12:08
24 5:56 18:04 12:08
28 5:58 18:05 12:07
January 1 5:59 18:06 12:07
11 6:04 18:11 12:07
27 6:09 18:16 12:07
Latitude=+40
December 4 7:06 16:35 9:29
8 7:09 16:35 9:26
12 7:13 16:35 9:22
16 7:16 16:36 9:20
20 7:18 16:38 9:20
24 7:20 16:40 9:20
28 7:21 16:42 9:21
January 1 7:21 16:43 9:22
11 7:22 16:54 9:32
27 7:14 17:12 10:58
31 7:10 17:17 10:07
Latitude=+60
December 4 8:41 14:59 6:18
8 8:48 14:56 6:08
12 8:54 14:54 6:00
16 8:58 14:53 5:55
20 9:02 14:54 5:52
24 9:03 14:56 5:53
28 9:03 15:00 5:57
January 1 9:03 15:02 5:59
11 8:54 15:22 6:28
27 8:27 15:59 7:32
31 8:18 16:10 7:52
.....................................................................
From the above we see that:
Lat 0 Lat +40 Lat +60
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Shortest Days ........ December 20 December 20
Earliest sunset November 2 December 8 December 16
Latest sunrise February 12 January 3 December 26
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The speed of the Sun on the sky can be found from its change in latitude and longitude:
Absolute
Day Distance(AU) Latitude Longitude Difference Degrees/
degrees deg min lat long Day
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Dec 4 0.9859 -0.41 252 7
8 0.9850 +0.09 256 10 .5 4.05 1.020
12 0.9845 +0.31 260 14 .22 4.07 1.019
16 0.9841 +0.04 264 19 .27 4.08 1.022
20 0.9837 -0.46 268 23 .50 4.07 1.025
24 0.9835 -0.76 272 27 .30 4.07 1.020
28 0.9833 -0.64 277 33 .12 5.1 1.275
Jan 4 0.9832 -0.37 282 54 .27 5.35
8 0.9832 -0.41 286 59 .04 4.08 1.020
12 0.9834 -0.05 291 3 .36 4.07 1.021
16 0.9837 +0.47 295 8 .52 4.08 1.028
20 0.9839 +0.73 299 12 .26 4.07 1.020
24 0.9843 +0.49 303 16 .24 4.07 1.019
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Perihelion occurs around January 6th at a distance of 0.9832 AU. For December, and January I used the 1996 ephemeris, so there is a break between December 28 and January 4. The point is that the speed of the Earth in its orbit, reflected in the Sun's ecliptic latitude and longitude, is not constant during the December Solstice, and although it is about 1 degree per day, it varies by up to 0.3 degrees per day around this mean value. Because 1 degree of angle equals 4 minutes of time this translates into a rate of change of the sunrise and sunset times of up to 4 x 0.3 or about a few minutes of time per day, in addition to the latitude of the observer on the Earth.