The official start of spring takes place at 4:58 p.m. on Wednesday, March 20, otherwise known as the Vernal (Spring) Equinox. Equinox refers to “equal night”. During the equinox, the sun’s rays are focused over the equator.
But check out the sunrise and sunset for the Quad Cities and you’ll see its not equal. Its actually an 8-minute difference.
The reason has to do with the sunlight entering the atmosphere. As it interacts with the composition and density of the atmosphere the direction of the sunlight is ‘refracted’ or bent. This allows us to see the sun’s upper edge to be visible from earth several minutes BEFORE it has risen over the horizon. This even holds true at sunset when you can see the sun for several minutes AFTER it has actually dipped under the horizon.
In the days and weeks ahead, we’ll experience even more daylight as we journey to the Summer Solstice, June 21st… The longest day of the year with 15 hours and 11 minutes of daylight.
Chief meteorologist Jame Zahara