Saturday, July 15, 2017

My assumptions are not always correct ( how the sun moves through the sky )

Originally posted on 7.14.15, updated on,

The sun goes from north to south, then north again during the day.  It makes an arc.  What this arc is , is not known by me, but it may be related to latitude.  In fact, I think it must be related to latitude.

If I am at 30 degrees north latitude, does that mean that it tracks 30 degrees?  No, because during the seasonal change, the arc changes.  It must change daily, as the season progresses.  Each day get shorter as the summer progresses, until the first day of fall, when the day and night are of equal length.

Perhaps the arc gets shallower?  No, because the sun would stay overhead all day, and that would cause the days to be hotter.

How can I look up answers to this question?  Or, what is the question?

Try this:  where does the sun track in the sky as the day progresses, and how does that change as the season progresses?

Actually, the old navigators of ancient time knew how the sun moves in the sky.  You can use the sun to tell time, for example.

I will leave this update, and study the questions.


This video doesn't answer the questions, but it does show how to use a pocket sundial.  The practical usefulness of this is not readily determined by moi.  Velly eenterstink, but shtupid.


What about navigational aids, like a sextant?  With the aid of a filter, it can make solar observations.

I'm thinking this will determine latitude.


A useful term may be referred to as the sun path.  A solargraph can be made for any location, or based upon the latitude of a location.

The original post follows:

So, that is why they should be tested to make sure that they are correct.

What's this crazy Texan saying this time?

Well, the sun doesn't move in the sky in a way that I assumed.  It moves in something of an arc with respect to east and west.  My assumption was that it moved in pretty much a straight line.

Now, the thing that I did expect was indeed true.  The sun rises north of the east-west line, and sets the same way.  But it does not stay on the north side of that east-west line.  This surprised me a little.

It makes an arc, taking it south across the east-west line, then turning back north towards the noon hour.  At that time, it is nearly directly overhead.  It gradually works back north to set well north of the east-west line.

So, what's the point?

With the sun being so hot and all, it might be well to consider how to align it with the expected movement of the sun in relation to your position.  In the summer months, you would like for the sun to be blocked in a way that gives maximum shade.  The opposite applies in the winter.

My assumption, once again, was that if you place your residence on the east-west line, and have the sun hit the north side in the summer, and the south side in the winter.  You can plan the building accordingly.  Keep as much of the building that you would like to get sun, like plants being grown for food, in the sun.  At the same time, keep as much of the sun off your building as possible, so as to help in climate control indoors.

An overhang can be in place in lieu of a building.  I would want a greenhouse to the north of my residence.  I think this plan will still work, but this gave me a result that I did not expect.

To protect in the morning, a wall may be necessary on the east side.  It may be desirable to have a wall on the west side too.

Not too much wall.  You want sun in the winter in order to warm up the place.

Learn something new every day.

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