Masson’s Blog - A Citizen’s Guide to Indiana » DST: Bad for Drinking

Doug posted a musing on whether the governor has legal authority to keep the bars open an extra hour early Sunday morning when the clocks change. It kicked off a discussion of sunrise/set times and time zones. Following were my contributions (most recent to oldest).

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Since it takes the sun about 15½ minutes to pass overhead from Indianapolis to the middle of our nearest time zone (90 degrees longitude), the corresponding times to 7 am and 5 pm would be about 6:44:32 am and 4:44:32 pm for Indianapolis.

So if Indiana were back in the central time zone again, we would expect to see the sunrise after 6:45 am from about Nov 29 to Feb 9 and the sunset before 4:45 pm from about Oct 31 to Jan 15.

This was the norm for Indiana on central time until the 1960's when most of the state went to year-round central daylight time (aka eastern standard time).

Bill
Fri, 9 Mar 2007, 7:43 am EST

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"T" wrote, "And those of us who’ve hated the pre-5pm sunsets can’t wait…"

Although Hoosiers are not very used to them, pre-5pm sunsets are at least normal for our latitude.

Simplifying, it would be reasonable to expect that the sun would rise after 7 am and set before 5 pm during the time of the year that there is less than 10 hours of sunlight (5 before midday and 5 after).

Indianapolis has less than ten hours of daylight from about Nov 15 until Jan 26 -- just under 2½ months.

Before there were time zones, Indianapolis and everyone due east and west around the world (latitude of 39.8 degrees north) had their sunrise after 7 am the 2½ or so months from about Nov 28 until February 9 and had their sunset before 5 pm the 2½ or so months from Oct 31 until January 15.

If you look at the USNO riseset figures for the "sister" cities of Indianapolis at about our latitude and very near the center of their time zones (Philadelphia, St. Louis, Denver, and Reno), you can see that this is very typical for our latitude.

http://aa.usno.navy.mil/data/docs/RS_OneYear.html#forma

Most of us in Indiana just had full-time central daylight time (aka eastern standard time) for so long, which amounted to about 45 minutes of year-round daylight saving time for our longitude, that these times seem kind of unusual to us, although they are really typical for our distance from the equator.

Bill
Fri, 9 Mar 2007, 7:14 am EST

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Hi, Doug. Thanks for the post. I had seen the news item, but had not thought about it going against the concept of the executive branch "executing" the laws duly passed by the legislative branch.

We seem to have enough trouble these days with legislation from the judicial branch, without the executive branch jumping in as well.

By the way, I think you're in the Lafayette area. It's just a little quibble, but the USNO gives a sunrise of 8:06 am for Lafayette on 11 March 2007 with DST.

http://aa.usno.navy.mil/data/docs/RS_OneYear.html#forma

Indy is only 8:03 am.

However, I am a big fan of establishing what is the baseline for reasonable, and also a fan of earlier sunrises for Indiana. The "normal" or "typical" sunrise time for locations at Indiana's latitude is 7:18 am. Before DST was shifted back to the second Sunday of March, it would have been 6:18 am. You can confirm this pretty easily by plugging in cities near Indiana's latitude and near the center of their time zones into the USNO page.

Philadelphia is 6:19 am (pre DST), Saint Louis 6:19 am, Denver 6:18 am, Reno 6:17 am.

Between being in the wrong time zone and going on DST earlier, the Hoosiers like me who like to see the sun in the morning are really getting robbed.

Regards, Bill Starr
Columbus, Indiana
Thu, 8 Mar 2007, 7:17 pm EST

Masson’s Blog - A Citizen’s Guide to Indiana » DST: Bad for Drinking