Sunday, 14 March 2010

Rants

Saving daylight again


Reminder: If you live in (most of) the U.S., and you haven’t reset your clock, you may want to do so before you forget (again).

Time again to haul out the daylight savings chart...

The chart reads from the bottom up (days of the year) and left to right.
Violet areas are darkness, the orange border is “civil twilight.”


...and take a look at what happened at 2:00 this morning.

For those of us here in Indianapolis, when we step out the door this morning, we’ll be finding it much darker than it was a day or so ago. We had just managed a sunrise before 7:00 (or would have, if it hadn’t been pouring rain yesterday), but this morning’s sunrise has been bumped back to almost 8:00.  We won’t see the sun peek over the horizon before 7:00 until April 20 - more than a month from now.  In fact, at 7:00 we’re all the way back unto what the astronomers call “nautical twilight,” which is as good as total darkness for those of us in urban areas.

At the other end of the day, those of us whose homeward commute ends around 7:00 will suddenly find it full daylight all the way until we pull in the drive. The extra end-of-day sunlight is probably a good thing, as everyone on the road will be dozy from having gotten up an hour earlier Monday morning.

Worth it?  It’ll take me a week or so to get my biorhythms adjusted, and the later sunrise won’t help.

My previous rants about DST are here and here.  For the OCD-ers among us, I’ve put a 2010 version of my earlier “How dark is it?” charts below the break...

How dark is it? - 2010 versions!


How dark is it at 6 a.m.?

without Daylight Saving:
Full Darkness January 1 - February 2051 days
Astronomical Twilight February 21 - March 1321 days
Nautical Twilight March 14 - April 220 days
Civil Twilight April 3 - April 1917 days
DaylightApril 20 - August 19122 days
Civil TwilightAugust 20 - September 1729 days
Nautical TwilightSeptember 18 - October 1932 days
Astronomical TwilightOctober 20 - November 1931 days
Full DarknessNovember 20 - December 3142 days
with Daylight Saving:
Full Darkness January 1 - February 2051 days
Astronomical Twilight February 21 - March 13
(clocks go ahead March 14)
21 days
Full DarknessMarch 14 - March 3017 days
Astronomical TwilightMarch 31 - April 1819 days
Nautical TwilightApril 19 - May 1426 days
Civil TwilightMay 15 - July 18
(no Daylight: earliest sunrise 6:16)
65 days
Nautical TwilightJuly 19 - August 2134 days
Astronomical TwilightAugust 22 - September 2131 days
Full Darkness
September 22 - November 6
(clocks go back November 7)
46 days
Astronomical TwilightNovember 7 - November 1913 days
Full DarknessNovember 20 - December 3142 days

How dark is it at 7 a.m.?
without Daylight Saving:
Astronomical TwilightJanuary 1 - January 1616 days
Nautical TwilightJanuary 17 - February 2237 days
Civil TwilightFebruary 23 - March 1218 days
DaylightMarch 13 - October 20222 days
Civil TwilightOctober 21 - November 1526 days
Nautical TwilightNovember 16 - December 2540 days
Astronomical TwilightDecember 26 - December 316 days
with Daylight Saving:
Astronomical TwilightJanuary 1 - January 16
16 days
Nautical TwilightJanuary 17 - February 22
37 days
Civil TwilightFebruary 23 - March 12
18 days
DaylightMarch 13
Only one day... oh, the agony!
(clocks go ahead March 14)
1 day
Nautical TwilightMarch 14 - April 1
19 days
Civil TwilightApril 2 - April 19
18 days
DaylightApril 20 - August 19122 days
Civil TwilightAugust 20 - September 17
29 days
Nautical TwilightSeptember 18 - October 1932 days
Astronomical TwilightOctober 20 - November 6
(clocks go back November 7)
18 days
Civil TwilightNovember 7 - November 15
9 days
Nautical TwilightNovember 16 - December 25
40 days
Astronomical TwilightDecember 26 - December 31
6 days

How dark is it at 8 a.m.?
without Daylight Saving:
Civil TwilightJanuary 1 - January 21
21 days
DaylightJanuary 22 - December 17
330 days
Civil TwilightDecember 18 - December 31
14 days
with Daylight Saving:
Civil TwilightJanuary 1 - January 21
21 days
DaylightJanuary 22 - October 20
272 days
Civil TwilightOctober 21 - November 6
(sun rises after 8:00 DST)
17 days
DaylightNovember 7 - December 17
41 days
Civil TwilightDecember 18 - December 31
14 days

How dark is it at 8 p.m.?
without Daylight Saving:
Full Darkness January 1 - February 22
53 days
Astronomical Twilight February 23 - March 24
30 days
Nautical Twilight March 25 - April 2835 days
Civil Twilight April 29 - May 22
24 days
DaylightMay 23 - July 30
69 days
Civil TwilightJuly 31 - August 21
22 days
Nautical TwilightAugust 22 - September 10
20 days
Astronomical TwilightSeptember 11 - September 29
19 days
Full DarknessSeptember 30 - December 31
93 days
with Daylight Saving:
Full Darkness January 1 - February 2253 days
Astronomical Twilight February 23 - March 13
(clocks go ahead March 14)
19 days
Nautical Twilightnone
0 days
Civil TwilightMarch 14 - March 22
9 days
DaylightMarch 23 - September 11
173 days
Civil TwilightSeptember 12 - September 27
16 days
Nautical TwilightSeptember 28 - October 18
21 days
Astronomical TwilightOctober 19 - October 31
13 days
Full DarknessNovember 1 - December 3161 days

How dark is it at 9 p.m.?
without Daylight Saving:
Full Darkness January 1 - April 14
104 days
Astronomical TwilightApril 15 - May 13
29 days
Nautical TwilightMay 14 - August 4
No Civil Twilight or Daylight,
latest sunset is 8:17 p.m.
83 days
Astronomical TwilightAugust 5 - August 27
23 days
Full DarknessAugust 28 - December 31126 days
with Daylight Saving:
Full Darkness January 1 - March 13
72 days
Astronomical TwilightMarch 14 - March 24
11 days
Nautical TwilightMarch 25 - April 28
35 days
Civil TwilightApril 29 - May 22
24 days
DaylightMay 23 - July 30
(latest sunset 9:17p DST)
69 days
Civil TwilightJuly 31 - August 2122 days
Nautical TwilightAugust 22 - September 10
20 days
Astronomical TwilightSeptember 11 - September 29
19 days
Full DarknessSeptember 30 - December 3193 days

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