Re: temporal hour including refraction
Dear David, You say, in the context of calculating solar azimuth that... Refraction has no effect on azimuth... Hmmm. This is absolutely true but, alas, the truth may well throw a beginner. Imagine calculating the azimuth of sunrise and going out with a friend one morning before dawn and pointing confidently where the sun will rise. Unless your calculation takes account of refraction you will have the time of sunrise wrong and hence the azimuth. Refraction means that the sun appears to rise before naive calculation says it will and, hence, its azimuth will be displaced. One of the great things about sundials is that even the simplest problem gets tougher once you look at it carefully! Frank King Cambridge, U.K. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: temporal hour including refraction
Refraction affects apparent altitude at a particular time. The apparent azimuth at a particular time does not change. But the time of sunrise/sunset is changed due to refraction, so therefore there is a different solar azimuth at this adjusted time. On 2013-11-13 11:28, Frank King wrote: Dear David, You say, in the context of calculating solar azimuth that... Refraction has no effect on azimuth... Hmmm. This is absolutely true but, alas, the truth may well throw a beginner. Imagine calculating the azimuth of sunrise and going out with a friend one morning before dawn and pointing confidently where the sun will rise. Unless your calculation takes account of refraction you will have the time of sunrise wrong and hence the azimuth. Refraction means that the sun appears to rise before naive calculation says it will and, hence, its azimuth will be displaced. One of the great things about sundials is that even the simplest problem gets tougher once you look at it carefully! Frank King Cambridge, U.K. -- --- https://lists.uni-koeln.de/mailman/listinfo/sundial
R: temporal hour including refraction
I always thought that ancient dials do not take refraction into account.Am I
wrong ?Gian
Messaggio originale
Da: noa...@hotmail.com
Data: 13/11/2013 14.44
A: Sundial Listsundial@uni-koeln.de
Ogg: temporal hour including refraction
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I need some assistance. I understand the formula to calculate the change
in altitude of the sun due to refraction.
http://en.wikipedia.org/wiki/Atmospheric_refraction#Calculating_refraction
What I can’t figure out is once altitude is changed what does that do to
all the other co-ordinates of the sun’s position.
What I am looking for is a way to calculate the temporal hour including
refraction, which is what you would see on an actual ancient sundial.
My problem is that the results that I get for the temporal hour including
refraction can be up to a fifteen minute difference at the 11th temporal hour,
which doesn’t seem right.
I am obviously not doing something right.
Any help would be appreciated.
Thanks,
Noam Kaplan
031:39:06 N
035:07:35 E
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Re: 08:09:10 11/12/13
I too strongly agree with Paul. The /MM/DD format sorts numerically; something that I gravitated to when a lad with database set-up and administration. This format also seems the most logical to me. In the grand scope of things, the millenium, century, year, month, day typically take precedence in that order. And now that we increasingly are interacting with a global market - a consistant, logical, and readily understood data format seems as important as ever Thad Weakley American expat in Montreal, Quebec Sunclocks North America sunclock...@icloud.com wrote: = This has always been a pet peeve of mine! All of these differing date formats are confusing, as you can never really be sure which one people are using. Here in Canada, it's even worse because some people put the month first like in the USA and others put the day first and yet others put the year first! Nobody can be sure if something like 10/11/12 means October 11th 2012, November 10th 2012 or November 12th 2010! At least now that we're in 2013, some of that confusion is gone for the next 87 years. I think that the best way which everyone in the world understands is to start a four digit year: /mm/dd, and all the confusion goes away with the simple addition of two characters. Plus the dates can be easily sorted numerically. It's pretty much the only date format I ever use unless I spell out the month. Paul Ratto SunClocks North America --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Peter Mayer Discipline of Politics International Studies (POLIS) School of History Politics http://www.arts.adelaide.edu.au/historypolitics/ The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8313 5609 Fax : +61 8 8313 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: 08:09:10 11/12/13
As for y/m/d, I completely agree, but for a full sort, we should also write hh:mm:ss ! Dave Sent from my iPad On Nov 13, 2013, at 1:43 PM, Thaddeus Weakley thadweak...@yahoo.com wrote: I too strongly agree with Paul. The /MM/DD format sorts numerically; something that I gravitated to when a lad with database set-up and administration. This format also seems the most logical to me. In the grand scope of things, the millenium, century, year, month, day typically take precedence in that order. And now that we increasingly are interacting with a global market - a consistant, logical, and readily understood data format seems as important as ever Thad Weakley American expat in Montreal, Quebec Sunclocks North America sunclock...@icloud.com wrote: = This has always been a pet peeve of mine! All of these differing date formats are confusing, as you can never really be sure which one people are using. Here in Canada, it's even worse because some people put the month first like in the USA and others put the day first and yet others put the year first! Nobody can be sure if something like 10/11/12 means October 11th 2012, November 10th 2012 or November 12th 2010! At least now that we're in 2013, some of that confusion is gone for the next 87 years. I think that the best way which everyone in the world understands is to start a four digit year: /mm/dd, and all the confusion goes away with the simple addition of two characters. Plus the dates can be easily sorted numerically. It's pretty much the only date format I ever use unless I spell out the month. Paul Ratto SunClocks North America --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Peter Mayer Discipline of Politics International Studies (POLIS) School of History Politics http://www.arts.adelaide.edu.au/historypolitics/ The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8313 5609 Fax : +61 8 8313 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
date
There's an international standard for all this. See: http://www.bing.com/search?q=iso+standard+dateqs=nform=QBLHpq=iso+standard+datesc=1-17sp=-1sk=cvid=38d7c3155b184da8bfa7fddd9c3526c2 Frederick Jaggi Horas Non Numero Nisi Serenas --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: 08:09:10 11/12/13
Good comment and a logical alternative to the confusion. If people use MS Office and wish to use this format, it must be changed in Control Panel. When the pattern is added, the dates in Excel, Word, etc. default to the new format, at least the short date. Open Office seems to be able to handle any format regardless of Control Panel settings. But would logic catch on? From: Thaddeus Weakley thadweak...@yahoo.com To: sundial@uni-koeln.de Sent: Wednesday, November 13, 2013 4:43 PM Subject: Re: 08:09:10 11/12/13 I too strongly agree with Paul. The /MM/DD format sorts numerically; something that I gravitated to when a lad with database set-up and administration. This format also seems the most logical to me. In the grand scope of things, the millenium, century, year, month, day typically take precedence in that order. And now that we increasingly are interacting with a global market - a consistant, logical, and readily understood data format seems as important as ever Thad Weakley American expat in Montreal, Quebec Sunclocks North America sunclock...@icloud.com wrote: = This has always been a pet peeve of mine! All of these differing date formats are confusing, as you can never really be sure which one people are using. Here in Canada, it's even worse because some people put the month first like in the USA and others put the day first and yet others put the year first! Nobody can be sure if something like 10/11/12 means October 11th 2012, November 10th 2012 or November 12th 2010! At least now that we're in 2013, some of that confusion is gone for the next 87 years. I think that the best way which everyone in the world understands is to start a four digit year: /mm/dd, and all the confusion goes away with the simple addition of two characters. Plus the dates can be easily sorted numerically. It's pretty much the only date format I ever use unless I spell out the month. Paul Ratto SunClocks North America --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Peter Mayer Discipline of Politics International Studies (POLIS) School of History Politics http://www.arts.adelaide.edu.au/historypolitics/ The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8313 5609 Fax : +61 8 8313 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: 08:09:10 11/12/13
By my experience, logic rarely catches on and tradition usually wins out... On Nov 13, 2013, at 7:11 PM, Douglas Vogt dbv...@yahoo.com wrote: Good comment and a logical alternative to the confusion. If people use MS Office and wish to use this format, it must be changed in Control Panel. When the pattern is added, the dates in Excel, Word, etc. default to the new format, at least the short date. Open Office seems to be able to handle any format regardless of Control Panel settings. But would logic catch on? From: Thaddeus Weakley thadweak...@yahoo.com To: sundial@uni-koeln.de Sent: Wednesday, November 13, 2013 4:43 PM Subject: Re: 08:09:10 11/12/13 I too strongly agree with Paul. The /MM/DD format sorts numerically; something that I gravitated to when a lad with database set-up and administration. This format also seems the most logical to me. In the grand scope of things, the millenium, century, year, month, day typically take precedence in that order. And now that we increasingly are interacting with a global market - a consistant, logical, and readily understood data format seems as important as ever Thad Weakley American expat in Montreal, Quebec Sunclocks North America sunclock...@icloud.com wrote: = This has always been a pet peeve of mine! All of these differing date formats are confusing, as you can never really be sure which one people are using. Here in Canada, it's even worse because some people put the month first like in the USA and others put the day first and yet others put the year first! Nobody can be sure if something like 10/11/12 means October 11th 2012, November 10th 2012 or November 12th 2010! At least now that we're in 2013, some of that confusion is gone for the next 87 years. I think that the best way which everyone in the world understands is to start a four digit year: /mm/dd, and all the confusion goes away with the simple addition of two characters. Plus the dates can be easily sorted numerically. It's pretty much the only date format I ever use unless I spell out the month. Paul Ratto SunClocks North America --- https://lists.uni-koeln.de/mailman/listinfo/sundial -- Peter Mayer Discipline of Politics International Studies (POLIS) School of History Politics http://www.arts.adelaide.edu.au/historypolitics/ The University of Adelaide, AUSTRALIA 5005 Ph : +61 8 8313 5609 Fax : +61 8 8313 3443 e-mail: peter.ma...@adelaide.edu.au CRICOS Provider Number 00123M --- This email message is intended only for the addressee(s) and contains information that may be confidential and/or copyright. If you are not the intended recipient please notify the sender by reply email and immediately delete this email. Use, disclosure or reproduction of this email by anyone other than the intended recipient(s) is strictly prohibited. No representation is made that this email or any attachments are free of viruses. Virus scanning is recommended and is the responsibility of the recipient. --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: 08:09:10 11/12/13
On Wed, Nov 13, 2013 at 03:01:46PM -0800, Dave Bell wrote: As for y/m/d, I completely agree, but for a full sort, we should also write hh:mm:ss ! As in ISO 8601? date(1) ... -I[TIMESPEC], --iso-8601[=TIMESPEC] output date/time in ISO 8601 format. TIMESPEC=`date' for date only (the default), `hours', `minutes', `seconds', or `ns' for date and time to the indicated precision. karl@redgum:~$ date -Is 2013-11-14T11:42:17+1100 Karl --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: temporal hour including refraction
No you're right! In all the methods to calculate or draw sundials, geometric or analytic, the Sun is always considered punctiform, and reduced to its center, and no account is taken of refraction, of the lowering of the horizon (horizon dip), of other astronomical phenomena such as parallax, etc.. Sunset and sunrise (for the calculation of temporary or italic hours) are always the instants when the center of the Sun crosses the theoretical horizon. Even Islamic astronomers, who well knew the phenomenon of refraction, do not take into account of it in the calculation of sundials and of the prayers lines. Best Gianni Ferrari --- https://lists.uni-koeln.de/mailman/listinfo/sundial
