Capricorn: Dec.22-Jan.29 The Sundial Primer
created by Carl Sabanski
Capricorn: Dec.22-Jan.29

The Sundial Primer Index

DeltaCad Sundial Macros - Fer de Vries

Fer de Vries wrote a number of DeltaCad macros that can be used to generate horizontal analemmatic sundials. There are a total of 4 macros that will be discussed and you can get them all here

Fer de Vries has a couple of macros that generate nomographs of the the sun's azimuth relative to the time and date. This nomograph can be used as a sundial. Check it out!

Nomograph

And also a macro to draw the graph for the Equation of Time.

Equation of Time

Analemmatic Sundial 1

This analemmatic sundial is generated after the user enters the "latitude" of the sundial's location and the length of the "half long axis" (semi-major axis) of the ellipse as shown in Figure 1. It indicates local apparent or solar time and only draws the hour points for the full hours. A positive latitude results in a sundial for the Northern Hemisphere and a negative latitude a sundial for the Southern Hemisphere.

After the "OK" button is selected a small window appears that gives the dimension of the "half short axis" (semi-minor axis) of the sphere and the maximum length of half a day, "max half day in hours".

Figure 1: Analemmatic Sundial 1 Macro

Figure 1: Analemmatic Sundial 1 Macro

The name of a text file is also provided, "ANALEM1.txt" in this case, which contains the x and y co-ordinates of the hour points and date scale. This file is placed in the same directory as the macro and is shown in Figure 2.

Figure 2: Analemmatic Sundial 1 Co-ordinates

Figure 2: Analemmatic Sundial 1 Co-ordinates

Figure 3 shows the sundial drawing that is generated.

Figure 3: Analemmatic Sundial 1

Figure 3: Analemmatic Sundial 1

Analemmatic Sundial 2

This analemmatic sundial is generated after the user enters the "latitude", "local meridian" and "central meridian" of the sundial's location and the length of the "half long axis" (semi-major axis) of the ellipse as shown in Figure 4. Negative meridian numbers are east of Greenwich and positive numbers are west of Greenwich.

Figure 4: Analemmatic Sundial 2 Macro

Figure 4: Analemmatic Sundial 2 Macro

The x and y co-ordinates of the hour points and date scale for this sundial are stored in the text file "ANALEM2.txt.

The sundial drawn with this macro is shown in Figure 5. Notice the hour points are slightly rotated. The hour points for this sundial have been corrected for longitude and indicate zonal solar time.

Figure 5: Analemmatic Sundial 2

Figure 5: Analemmatic Sundial 2

Analemmatic Sundial 3

This analemmatic sundial is generated after entering the same information as required for the previous sundial. The sundial includes the addition of day circles and is shown in Figure 6. The day circles intersect the ellipse at the times of sunrise and sunset.

Figure 6: Analemmatic Sundial 3

Figure 6: Analemmatic Sundial 3

The x and y co-ordinates of the hour points and date scale for this sundial are stored in the text file "ANALEM3.txt.

Analemmatic Sundial 3 Modified

This analemmatic sundial is generated after the user enters the same information as for the previous sundial. However there is now a selection for drawing hour points at 10, 15 and 30 minute intervals as well as 1 hour intervals. This is shown in Figure 7.

Figure 7: Analemmatic Sundial 3 Modified Macro

Figure 7: Analemmatic Sundial 3 Modified Macro

The sundial drawing generated is shown in Figure 8. As well as having the additional hour points as set of new lines are also drawn. These are the blue lines and they are drawn from a particular date point on the date scale to the points on the ellipse for sunrise and sunset for that date. Note that all the lines pass through two small areas on the east-west axis of the ellipse. An average point can be chosen and markers added to the sundial layout. Using a string on the completed dial, one end can be held on a particular date on the date scale and by stretching the string through one of the markers, the time of sunrise or sunset can be estimated.

Figure 8: Analemmatic Sundial 3 Modified

Figure 8: Analemmatic Sundial 3 Modified

The x and y co-ordinates of the hour points and date scale for this sundial are stored in the text file "ANALEM3.txt.