The clocks show the "exact" time at the given location; determined by offsetting by 1 hour for every 15° of longitude away from 0°. (Someone 1° away from 0° will be off by 4 minutes.) The sun will be exactly over head at the location when the clock reads 12:00:00. Locations are determined using the Google JavaScript Geocoding API and the time is determined using the computer's clock.