GraphDark Hint - Rainbow Visibility

  Because the visibility of a rainbow depends on the altitude of the sun there are times when the sun is too high. On this timetable the area highlighted in red shows when the sun is below 42 degrees and part of a rainbow would be visible above the horizon. The orange area is the time when only a secondary bow would be visible. Light blue represents times when the sun is too high, the darker blues are when it is below the horizon.

See below for details on how to reproduce this diagram.

 
   
 
When GraphDark is installed the default is to show midnight across the middle of the timetable.
The first step is to set up the timetable to show midday instead.
Use Edit, Preferences, Timetable Display, Times and check the Day Mode box.

Return to the graph and choose your site from the Where box.
From the What box select Sun then click on the M button, just to the right, to select an altitude mask.
Choose Rainbow from the list and click OK, the graph will be drawn immediately.

A typical display shows about 3 months on one screen. To get more days on the screen, as shown in the example:
Edit, Preferences, Timetable Display, Day Width and type 3 into the Pixels box.


Return to Glows Bows and Haloes
 

   Richard Fleet 2004

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