I know you are but you seem to be confusing what happens at sunset with what happens at noon.
I donāt think so. The sun also sets on its southern limit in winter in the northern hemisphere in winter - as well as having the lowest noon
winter solstice i meanā¦
Have you noticed that the time of the solar noon varies during the year, and, also according to your location in relation of the meridian that determines your time zone. The first because the axis of the earth does not rotate as we circle the sun.
Where I live, the time of the solar noon varies during the year approximately between 12:02 and 12:22 (13:22 DST). This explains the values in Daveās table. For me, the solar noon and the noon in my clock never coincide, if you live nearer to the time zone meridian they do so only twice a year. Obviously it is the the solar noon that is about halfway between sunset and solstice, not the noon in your clock.
Anssi
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Yes but i"m not talking about noon - Iām talking about sunset. The southerly limit of the setting sun in winter should coincide with the day of the winter solsticeā¦
I think we are talking in circles here. Could you provide the SketchUp file you currently work with? You could even replace your model by a simple vertical block with some notes of what you expect and what SketchUp does wrong for shadows. Just to be clear in answering your question.
Some comments:
Before using what Su shows one should under stand where the data are obtained. There are a number of on line calculators but there is one official site which I think is the US Naval Observatory;
It is is my under standing their reports includes atmospheric refraction in their predictions;
In looking at what GE pro uses it is IOPG ( Internataional Association of OIL and Gas Producers ) and it has a number of data tables EPSG Geodetic Data Set http://www.epsg.org/ it uses to draw data from.
@stefsketchup : You are living in the SOUTHERN HEMISPHERE ?
Or , better asked, the POI is at the SOUTHERN HEMISPHERE ?
Anssi,
That āsuncalcā website is great!!! Thank you.
It is simple and easy to work with.
Agree - but why donĀ“t You "like " him ?
try putting a vertical block in e.g. Boulder and tell me if the last shadow before sunset in winter changes direction on the winter solstice. if it doesnāt, itās wrong
This (see bold text) has nothing to do with SketchUp. Itās reality, see provided link.
So in fact I answered your question.
You donāt provide a model to show the exact problem and let us guess why shadows should change direction around sunset on dec.21
According to quote:[quote=āstefsketchup, post:33, topic:24091, full:trueā]
try putting a vertical block in e.g. Boulder and tell me if the last shadow before sunset in winter changes direction on the winter solstice. if it doesnāt, itās wrong
[/quote]
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That is also a great website. The earliest sunset here is on about dec.15 and the latest sunrise on about dec.27
Anssi
THIS - a big duh moment for me. I never knew I had to set the timezone manually - I always expected the software to take care of that if only you set the geo-location correctly. I did notice a few times though some differences in shadows compared to the shade on the actual location.
Reviving this old thread because I know more people who ran into this problem.
The time zone is set automatically but the offset for DST is not automatic.
My default template has the time zone set as -07:00. I have a location in Rom set but not yet selected.
After selecting the region the time has changed to +01:00.
I always enter the location manually but thanks for the additional info.Good to know.
Even then the time zone gets set automatically but still not the DST offset. 