Today, March 20, 2014, is the Vernal Equinox.
Here is an explanation from Environment Canada staff regarding what that means, and why the Charlottetown sunrise/sunset data appears to violate that definition.
An equinox in astronomy is the event when the sun can be observed to be directly above the Earth's equator, occurring around each year. More technically, the equinox happens when the sun is at one of two opposite points on the celestial sphere where the celestial equator and ecliptic intersect. In a wider sense, the equinoxes are the two days each year when the center of the Sun spends an equal amount of time above and below the horizon at every location on Earth.
This being said, the reason why the sunrise and sunset times show that the day is longer than the night on the date the equinox happens is due to the way sunrise and sunset times are calculated. Sunrise is the time when the upper edge of the sun becomes visible and sunset is the time when the upper edge of the sun disappears below the horizon. The time it takes for the sun to disappear completely below the horizon in the evening accounts for the fact that there is more than 12 hours of daylight on the day equinox.
Meteorological Inquiry Specialist
MSC National Inquiry Response Team ISO 9001:2008