Throwback Thursday: Daylight hours across time and location

Back in 2006, I wrote a script (in Perl!) to plot daylight hours over the year, given a location. From what I remember, I was curious about how it changed with the seasons: was it a straight line or a curve, and how did it look in the polar regions?

(If any image below looks blurry, open it in a separate tab or save it to disk to see it in actual size.)

Near North Pole (79°N). They see no Sun for half the year, and then it’s day non-stop. Note the curve of spread:

Near North Pole (79°N)

Anchorage, Alaska. Spikes in these graphs are due to daylight saving time turning on and off:

Anchorage, Alaska (61°N)

San Francisco, California:

San Francisco, California (37°N)

Singapore. It’s just 1° off the equator, and it shows:

Singapore (1°N)

Wellington, New Zealand. The graph is concave in Southern Hemisphere, where the seasons are reversed:

Wellington, New Zealand (41°S)

Antarctica, 79°S. Note how this is a complement of what we saw for the Arctic:

Antarctica (79°S)


These graphs were created from data in I wrote a script to parse off the values from those webpages and plot the graph using GD library. You can download the script. (Made available with permission from owner of that website.)

See also