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

The Sundial Primer Index

Sun Charts

The Sun Charts illustrated on this page were created using an on-line program at the web site of the University of Oregon Solar Radiation Monitoring Laboratory. If you would like a set of Sun Charts for your location please visit their Sun Chart Program web page at: http://solardat.uoregon.edu/SunChartProgram.html


If you have ever had an interest in solar energy you have probably seen a sun chart. The sun chart enables you to locate the position of the sun at any time of day, during any month and for any location. It is a plot of the sun's altitude versus azimuth at different times throughout a given day. This is the sun's path for that day. This can be done for any day of the year. A sun chart will have plots for the sun's path for a particular day each month. If the times of day on each sun path are connected lines will be drawn that represent the hours of the day. A new sun chart is required to illustrate the sun's path at different latitudes.

Figure 1 is an example of a sun chart for latitude 50 N.

Figure 1: Sun Charts - Solar Time

Figure 1: Sun Charts - Solar Time

A separate sun chart is generated for each half of the year. The sun's azimuth is varies from 0 to 360  and its elevation from 0 to 90. The sun's path for a particular day each month is shown in blue and the lines for the hours of the day are in red. The time is local apparent time or solar time. Sun charts can also be created that show clock time and the hour lines are shifted for longitude correction and each hour line will show half the analemma. This can be seen in Figure 2 for a longitude of 95 W.

Figure 2: Sun Charts - ClockTime

Figure 2: Sun Charts - Clock Time

Sun charts normally only show time lines for the full hours. Even so, a lot of useful information can be obtained from sun charts for sundial design. Figure 3 illustrates this.

Figure 3: Sun Chart Sundial Data

Figure 3: Sun Chart Sundial Data

Figure 3 is the sun chart for a location at a latitude of 50 in the Northern Hemisphere. It should be noted that the sun charts for the Northern Hemisphere have a solar azimuth range of 0 to 360. The sun charts for the Southern Hemisphere have a solar azimuth range of -180 to 180. Note that the sun is due east at a solar azimuth of 90 for both the Northern and Southern Hemispheres and due west at 270 for the Northern Hemisphere and -90 for the Southern Hemisphere.

The following dialling data can be obtained from the sun chart:

  • Time of sunrise.

  • Time of sunset.

  • The time range for a horizontal sundial - sunrise to sunset.

  • The time range for vertical direct south sundial - sun due east to sun due west.

  • The time range for a vertical direct east sundial - sunrise to noon.

  • The time range for a vertical direct west sundial - noon to sunset.

  • The time range for a vertical direct north sundial - sunrise to sun due east and sun due west to sunset.

It is also possible to get the time range for a vertical declining sundial. This is a vertical sundial that is turned east or west of due south. As an example take a vertical sundial that declines15 east. The time range for this sundial will be those times associated with the solar azimuths of 75 and 255 in Figure 3.

It is also possible to obtain a polar sun path chart. Figure 4 is an example of a polar sun chart for latitude 50 N.

Figure 4: Polar Sun Chart - Solar Time

Figure 4: Polar Sun Chart - Solar Time


Take a look at the next two figures. These are sun charts for the Arctic Circle, 66 33' 21" N, and the Antarctic Circle,  66 33' 21" S. The sun reaches a maximum elevation at the summer solstice of: (90 - 66.56) + 23.44 = 46.88

Figure 5 - Sun Chart for the Arctic Circle

Figure 5: Sun Chart for the Arctic Circle

Figure 6 - Sun Chart for the Antarctic Circle

Figure 6: Sun Chart for the Antarctic Circle

On the day of the Summer Solstice for the Northern and Southern Hemispheres, the sun is above the horizon a full 24 hours. The sun is due east at approximately 6:45 a.m. and due west at approximately 5:15 p.m. This means that a vertical direct south sundial at the Arctic Circle and a vertical direct north sundial at the Antarctic Circle will have the sun shining on them for approximately 10.5 hours. The interesting thing though is that a vertical direct north sundial at the Arctic Circle and a vertical direct south sundial at the Antarctic Circle will have the sun shining on them for approximately 13.5 hours.

As you can see, sun charts can provide some very interesting information.

If you are interested in seeing sun charts for the Equator and the North (South) Pole then continue on to:

More Sun Charts