The yellow section shows when the sun is up, and how this changes over the year.
Use the time-of-day scales, on the left and right, and the month scale on the top and bottom, to tell approximately when sunrise and sunset occur.
See Sunrise, Sunset, and Daylight for more info.
The sunrise and sunset times shown in the chart are approximate.
They are accurate for the latitude, and show the precise amount of daylight,
but the rise and set times may be offset (up or down in the chart)
since I don't have an automated way of matching time zones to longitudes.
The charts are made assuming that the location is in the middle of an evenly spaced time zone.
For precise times see US Naval Observatory.
For WHIDBEY ISLAND NAS, WA, use latitude 48°21'00N and longitude 122°40'00W in the form.
You'll need to know the time zone of the location.