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Index of Subjects --20cf307f30ba85c71d050bdba68f Content-Type: text/plain; charset=UTF-8 Andy I've had this question a few times recently. As Burkhard and others point out (with much more expertise than I possess!), the days do get longer beginning Dec 22, starting in increments of a few seconds. I think the discrepancy lies in the fact that popular public sites - e.g. Environment Canada's Weatheroffice, CBC.ca, WeatherNetwork, etc - report sunrise and sunset times rounded to minutes, dropping the seconds. By this unit of measure there is no quantifiable net change in daylight for several days after the solstice - the 27th, I believe, this year. However, have faith - it is happening ! ;-) Also, as Burkhard noted, timeanddate.com is an excellent site for this type of info, and it has all kinds of other widgets - calculators, world clocks, timers, and an excellent API. I used to have a site that calculated cumulative gain over a given period - usually a month - but can't seem to lay my hands on it right now. It is out there somewhere, I'm sure. Regards, Jamie On 27 December 2014 at 14:21, Burkhard Plache <burkhardplache@gmail.com> wrote: > You are (I am guessing) making assumptions regarding the > definitions of the coordinates (here: latitude) that are incorrect. > The altitude is measured / calculated from local horizontal, > which differs from the angle when connecting the 45 degree point > to the center of the ellipsoid. > If you make an over-ellipsed sketch (e.g., North-South being > half of East-West) the discrepancy should become clear. > Keep in mind, though, that e.g., 45 degree latitude in the > ellipsoid coordinate system is *not* obtained by drawing a 45 > degree line from the center of the ellipsoid. On the ellipsoid, > 45 degree latitude is where the local vertical stands at a 45 degree > angle versus the equator plane (or versus the rotational axis). > > Calculations in ellipsoid coordinates are unfortunately not > 'closed formula' but require numerical approximations. > > Burkhard > > > On Sat, Dec 27, 2014 at 11:02 AM, David & Alison Webster > <dwebster@glinx.com> wrote: > > Hi All, Dec 27, 2014 > > As an exercise in reasoning I attempted to calculate winter minimum > > altitude of the sun at solar noon for two locations Kings County (Lat of > > 44o44' given) and Halifax (Lat of 44o39' given). > > > > With the earth sliced in two along the meridian, minimum altitude > (Min), > > if my reasoning is correct, should be equal to > > Min = 90 -(Lat+23o26') > > But for Kings Co. I get Min = 21.83o lower than given of 21.9o by > 0.07o > > and for > > Halifax I get Min = 21.92o lower than given of 22.0o by 0.08o. > > Is this discrepancy due the the earth not being quite spherical or > > something else ? > > Yt, Dw, Kentville > > ----- Original Message ----- From: "Burkhard Plache" > > <burkhardplache@gmail.com> > > To: <naturens@chebucto.ns.ca> > > Sent: Thursday, December 25, 2014 1:31 PM > > Subject: Re: [NatureNS] why aren't the days getting longer > > > > > >> Tabulated sunrise / sunset times are given at: > >> http://www.timeanddate.com/sun/canada/halifax > >> > >> And indeed, the days *are* getting longer. > >> > >> Burkhard > >> > >> > >> ----- > >> No virus found in this message. > >> Checked by AVG - www.avg.com > >> Version: 2015.0.5577 / Virus Database: 4257/8805 - Release Date: > 12/25/14 > >> > > > -- Jamie Simpson Hantsport, NS --20cf307f30ba85c71d050bdba68f Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">Andy<div><br></div><div>I've had this question a few t= imes recently.=C2=A0 As Burkhard and others point out (with much more exper= tise than I possess!), the days do get longer beginning Dec 22, starting in= increments of a few seconds. =C2=A0</div><div><br></div><div>I think the d= iscrepancy lies in the fact that popular public sites - e.g. Environment Ca= nada's Weatheroffice, CBC.ca, WeatherNetwork, etc - report sunrise and = sunset times rounded to minutes, dropping the seconds. By this unit of meas= ure there is no quantifiable net change in daylight for several days after = the solstice - the 27th, I believe, this year.</div><div><br></div><div>How= ever, have faith - it is happening ! ;-)</div><div><br></div><div>Also, as = Burkhard noted, timeanddate.com is a= n excellent site for this type of info, and it has all kinds of other widge= ts - calculators, world clocks, timers, and an excellent API.=C2=A0 I used = to have a site that calculated cumulative gain over a given period - usuall= y a month - but can't seem to lay my hands on it right now.=C2=A0 It is= out there somewhere, I'm sure.</div><div><br></div><div>Regards,<br></= div><div><br></div><div>Jamie</div></div><div class=3D"gmail_extra"><br><di= v class=3D"gmail_quote">On 27 December 2014 at 14:21, Burkhard Plache <span= dir=3D"ltr"><<a href=3D"mailto:burkhardplache@gmail.com" target=3D"_bla= nk">burkhardplache@gmail.com</a>></span> wrote:<br><blockquote class=3D"= gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-= left:1ex">You are (I am guessing) making assumptions regarding the<br> definitions of the coordinates (here: latitude) that are incorrect.<br> The altitude is measured / calculated from local horizontal,<br> which differs from the angle when connecting the 45 degree point<br> to the center of the ellipsoid.<br> If you make an over-ellipsed sketch (e.g., North-South being<br> half of East-West) the discrepancy should become clear.<br> Keep in mind, though, that e.g., 45 degree latitude in the<br> ellipsoid coordinate system is *not* obtained by drawing a 45<br> degree line from the center of the ellipsoid. On the ellipsoid,<br> 45 degree latitude is where the local vertical stands at a 45 degree<br> angle versus the equator plane (or versus the rotational axis).<br> <br> Calculations in ellipsoid coordinates are unfortunately not<br> 'closed formula' but require numerical approximations.<br> <span class=3D"HOEnZb"><font color=3D"#888888"><br> Burkhard<br> </font></span><div class=3D"HOEnZb"><div class=3D"h5"><br> <br> On Sat, Dec 27, 2014 at 11:02 AM, David & Alison Webster<br> <dwebster@glinx.com> wrote:= <br> > Hi All,=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 Dec 27, 2014<br> >=C2=A0 =C2=A0 As an exercise in reasoning I attempted to calculate wint= er minimum<br> > altitude of the sun at solar noon for two locations Kings County (Lat = of<br> > 44o44' given) and Halifax (Lat of 44o39' given).<br> ><br> >=C2=A0 =C2=A0 With the earth sliced in two along the meridian, minimum = altitude (Min),<br> > if my reasoning is correct, should=C2=A0 be equal to<br> >=C2=A0 Min =3D 90 -(Lat+23o26')<br> >=C2=A0 =C2=A0 But for Kings Co. I get Min =3D 21.83o lower than given o= f 21.9o by 0.07o<br> > and for<br> > Halifax I get Min =3D 21.92o lower than given of 22.0o by 0.08o.<br> >=C2=A0 =C2=A0 Is this discrepancy due the the earth not being quite sph= erical or<br> > something else ?<br> > Yt, Dw, Kentville<br> > ----- Original Message ----- From: "Burkhard Plache"<br> > <<a href=3D"mailto:burkhardplache@gmail.com">burkhardplache@gmail.c= om</a>><br> > To: <<a href=3D"mailto:naturens@chebucto.ns.ca">naturens@chebucto.n= s.ca</a>><br> > Sent: Thursday, December 25, 2014 1:31 PM<br> > Subject: Re: [NatureNS] why aren't the days getting longer<br> ><br> ><br> >> Tabulated sunrise / sunset times are given at:<br> >> <a href=3D"http://www.timeanddate.com/sun/canada/halifax" target= =3D"_blank">http://www.timeanddate.com/sun/canada/halifax</a><br> >><br> >> And indeed, the days *are* getting longer.<br> >><br> >> Burkhard<br> >><br> >><br> >> -----<br> >> No virus found in this message.<br> >> Checked by AVG - <a href=3D"http://www.avg.com" target=3D"_blank">= www.avg.com</a><br> >> Version: 2015.0.5577 / Virus Database: 4257/8805 - Release Date: 1= 2/25/14<br> >><br> ><br> </div></div></blockquote></div><br><br clear=3D"all"><div><br></div>-- <br>= <div class=3D"gmail_signature"><div dir=3D"ltr"><div>Jamie Simpson<br></div= >Hantsport, NS<br></div></div> </div> --20cf307f30ba85c71d050bdba68f--
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