For a South vertical dial it is 45°
The orbit of the Sun are cut by the horizon and by the dial.
Moving to North from 45°, what the winter solstice orbit losses is more then
what the summer solstice orbit gains. It is the same thing moving to South
and changing winter with summer.
ciao Fabio
Hello All,
Today I saw a vertical wall dial with an adjustablegnomon/style that
has a hinge at the point where it connects with the dialplate.
The dial is a south facing model and 12 noon is directly on the centerline
of the dial and the gnomon. Obviously longitude and EoT correction would
John,
I think Fer's sundial program will tell you the amount of sunshine that any
particular site will receive, and I think it takes into account the
different sundial types and declinations. It will give you the sunrise and
sunset times as well.
It now has an easier name to spell as well, it
Here's something for you to think about.
If you ask the question: What is the best latitude(s) for a particular type
of sundial? How would you answer that question? How would you define best
latitude.
One way of defining best latitude(s) would be those latitudes where the
sundial type functions
Hi Mike:
The question you answered as was this: Which sundial type fuctions for the
maximum number of hours in a day? (You answered horizontal)
But the question I asked was this: What is the best latitude for a
particular sundial type (i.e.. direct south vertical wall dials in the
northern
Hi Mike:
The tricky part of my question is figuring out the total number of hours of
sunlight a particular sundial face receives in a year.
You said:
As for latitude, isn't it true that everywhere on earth gets an average of
12 hours of daylight over a year?
No that's NOT true! What does
If it were possible to calculate the total number of hours a sundial could
receive in a year, then this could be called its Efficiency Rating!
The rating would be in number of hours with the maximum possible rating of
12hrs. x 365 days = 12,365 hours. (ie a horizontal dial on the equator)
John
Hi Jim:
Yes Fer's Program and other programs will tell you the amount of sunshine
that any
particular site will receive, but that's only gives part of the answer
because it gives hours of sunshine at the site and not on the dial face.
(You're talking about Site Efficiency, not Sundial
Does this help?
Definition of Sundial Efficiency Rating: The percentage of total possible
hours (12,365 hrs.) of sunlight that falls on a particular sundials face in
one year. Its value is determined by the type of sundial, its orientation,
and its latitude. So every dial would have it's own
The rating would be in number of hours with the maximum possible rating of
12hrs. x 365 days = 12,365 hours. (ie a horizontal dial on the equator)
A horizontal dial anywhere?
At the equator, 12 hours every day
At the pole, 24 hours for half a year
Intermediate will average 12 hours over a year.
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