[NatureNS] why aren't the days getting longer

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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

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Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Andy<div><br></div><div>I&#39;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&#39;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&#39;t seem to lay my hands on it right now.=C2=A0 It is=
 out there somewhere, I&#39;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">&lt;<a href=3D"mailto:burkhardplache@gmail.com" target=3D"_bla=
nk">burkhardplache@gmail.com</a>&gt;</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>
&#39;closed formula&#39; 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 &amp; Alison Webster<br>
&lt;dwebster@glinx.com&gt; wrote:=
<br>
&gt; 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>
&gt;=C2=A0 =C2=A0 As an exercise in reasoning I attempted to calculate wint=
er minimum<br>
&gt; altitude of the sun at solar noon for two locations Kings County (Lat =
of<br>
&gt; 44o44&#39; given) and Halifax (Lat of 44o39&#39; given).<br>
&gt;<br>
&gt;=C2=A0 =C2=A0 With the earth sliced in two along the meridian, minimum =
altitude (Min),<br>
&gt; if my reasoning is correct, should=C2=A0 be equal to<br>
&gt;=C2=A0 Min =3D 90 -(Lat+23o26&#39;)<br>
&gt;=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>
&gt; and for<br>
&gt; Halifax I get Min =3D 21.92o lower than given of 22.0o by 0.08o.<br>
&gt;=C2=A0 =C2=A0 Is this discrepancy due the the earth not being quite sph=
erical or<br>
&gt; something else ?<br>
&gt; Yt, Dw, Kentville<br>
&gt; ----- Original Message ----- From: &quot;Burkhard Plache&quot;<br>
&gt; &lt;<a href=3D"mailto:burkhardplache@gmail.com">burkhardplache@gmail.c=
om</a>&gt;<br>
&gt; To: &lt;<a href=3D"mailto:naturens@chebucto.ns.ca">naturens@chebucto.n=
s.ca</a>&gt;<br>
&gt; Sent: Thursday, December 25, 2014 1:31 PM<br>
&gt; Subject: Re: [NatureNS] why aren&#39;t the days getting longer<br>
&gt;<br>
&gt;<br>
&gt;&gt; Tabulated sunrise / sunset times are given at:<br>
&gt;&gt; <a href=3D"http://www.timeanddate.com/sun/canada/halifax" target=
=3D"_blank">http://www.timeanddate.com/sun/canada/halifax</a><br>
&gt;&gt;<br>
&gt;&gt; And indeed, the days *are* getting longer.<br>
&gt;&gt;<br>
&gt;&gt; Burkhard<br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;&gt; -----<br>
&gt;&gt; No virus found in this message.<br>
&gt;&gt; Checked by AVG - <a href=3D"http://www.avg.com" target=3D"_blank">=
www.avg.com</a><br>
&gt;&gt; Version: 2015.0.5577 / Virus Database: 4257/8805 - Release Date: 1=
2/25/14<br>
&gt;&gt;<br>
&gt;<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>

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