Sun Data Display

The main box displays a scrolling Daily Summary List.  The list contains sun data for each day of your date range.  Every line has the day and date, dawn, time of sunrise, the sun’s azimuth position at sunrise, day length: hours and minutes between sunrise and sunset, time of sunset, the sun’s azimuth position at sunset and dusk.

Dawn:  The time each morning at which daylight first begins, the period of increasing light between dark and sunrise.  sunPATH calculates the point in time when there should be enough light from the sky for an exposure (“Magic Hour”.)  Terrain features and weather conditions can limit the available skylight.  (This is not astronomical, civil or nautical twilight.)  See “Magic Hour” in the Glossary.

Sunrise:  The time of day the sun’s apparent upper edge first appears at the eastern horizon (“true horizon”).  sunPATH calculates the time and azimuth when the TOP of the sun first appears at the “true horizon.” 

Sunset:  The time of day the sun’s apparent upper edge disappears below the western horizon (“true horizon”). sunPATH calculates the time and azimuth when the TOP of the sun finally disappears at the “true horizon.” 

All horizons are considered at sea level.  Note that the azimuth and time calculations for sunrise and sunset are based on the TOP of the sun. The azimuth and altitude calculations during the day are for the CENTER of the sun.  The calculations account for standard atmospheric refraction at sea level and ignore terrain features.

Dusk:  (Twilight) The evening period of waning light between sunset and dark, when the sun is below the horizon. sunPATH calculates the point in time when there should still be enough light from the sky for an exposure (“Magic Hour”.)   Terrain features and weather conditions can limit the available skylight.  (This is not astronomical, civil or nautical twilight.) See “Magic Hour” in the Glossary.

The Sun Position List for the selected day, is displayed in the small box at the lower-left of the window.  This list displays the sun’s position in half-hour or fifteen minute increments throughout the day for the selected day (highlighted line) of the Daily Summary List.  The azimuth and altitude measurements are for the center of the sun (azimuth the position on the horizon, altitude  height in the sky).  To select a different day for display in the Sun Position List, click on the desired day in the Daily Summary List.  The line will become highlighted and the program will compute the new sun position data.  This list also contains a “Shadow Factor” for each time increment.

The “Shadow Factor” allows you to determine the approximate length of shadows during the day.  You need to know the height of the object that will be casting the shadow to determine the length.
Shadow Length = Object Height x Shadow Factor.  
(e.g., Shadow Length = 10ft x 5.67   Shadow Length = 56.7ft)
The shadows change very quickly when the sun is low in the sky.

The note box at the lower-center of the window informs you if sunPATH made the calculations based on “True North” or “Magnetic North.”   Magnetic North indicates that Magnetic Declination was used in the calculation.   This allows you to use direct readings from your compass (a compass bearing).

Click on the “Graph” button to view a graphical plot of the Sun Position for the currently selected day.  To select a different day for display in the graph, click on the desired day in the Daily Summary List.  The line will become highlighted and sunPATH will compute the new sun position data.  Now click on the “Graph” button to view a new graph.
Click on the “Print” button to print reports for your date range.

Choose Print Option… under the File menu to change the number of days reported on each page of the printed report.  sunPATH will only print Shadow Factors when one day per report page is selected.  Shadows change dramatically from day to day.
When you are finished with the Sun Data Display, press the RETURN  key, click on the OK button or click on the Close Box.