This displays a list of where in the world the sun is currently rising or setting. The location circled on the maps will automatically be updated as sunrise or sunset happens in each location.
All times plotted and listed are local clock times, hence there will be steps in the lines as daylight saving adjustments are applied. Clicking the Select All button, then CTRL+C (or right-click - Copy) allows the information in the list to be copied onto the clipboard and then pasted into Word, Excel, etc.
The times of Dawn and Dusk can also be listed by ticking the "Display times of dawn and dusk" box, and then clicking the Calculate button. In the example below, the weather station on the Antarctic Peninsula does not have a dusk until Jan 14th in 2007, with only about 45 minutes of twilight on that day. The angle that the centre of the sun must be below the horizon in calculating the times here can be changed. 6.12 degrees is the threshold to calculate the time of Civil Twilight, around 12 degrees would be for Nautical Twilight, and 18 for Astronomical Twilight. It should be noted that in the example below, the threshold for the onset of twilight is very sensitive to the angle of 6.12 degrees. For example, changing the angle to 6.3 degrees means that twilight doesn't start until Jan 15th.
Clicking this menu option allows a more detailed analysis of the variation of sunrise and sunset times for a specific date across multiple locations. A typical use for this function could be to look at the revised times of sunrise in November in 2007 in parts of North America that have extended their period of operation of daylight saving. In order to do this, (for the last day that DST applied in 2007, ie 3rd Nov), change the date at the top of the screen below the main menus, select a country from the list on the right-hand side, eg United States, then click the Sunrise column to list locations with latest local time of sunrise first. This shows that in cities with populations exceeding one million in the United States, Grand Rapids in Michigan has the latest sunrise at 08:19 local time. Note that only locations with populations of >1,000,000 and Capital cities are listed because that is what is selected in the population threshold and continent filters at the top of the screen.
In the above example, clicking the "Show all places" tick box on, then clicking the Start/Refresh button will include all locations in the United States regardless of their population. Doing this again for the 3rd Nov 2007 shows that Point Hope in Alaska's north-west had the latest sunrise. Locations with "GSN" in the "Cont(inent)" column are weather stations. Both GSN and Photos locations do not correspond to population centres. The latest sunrise outside Alaska on 3rd Nov 2007 is at 08:22 in Williston (North Dakota), with a population of around 11,000.
The last column ("Radt") shows the amount of solar radiation that each location receives on the selected date (a top of atmosphere value not taking cloud cover, etc into consideration). During daylight hours the intensity of solar radiation varies according to the sun's elevation above the horizon. The maximum value possible is about 1.25 units at the poles on midsummer. Although the sun is only about 23 degrees high in elevation at the poles on midsummer, radiation is received for 24 hours in the day. The value is normalised such that locations on the equator receive 1 unit of solar radiation per day on the equinoxes. This radiation intensity is also shown graphically in the main Sun Times display: