(Charly Triballeau/AFP/Getty Images)

It's that time of year again when an hour disappears from the clock, making for bleary eyes and missed appointments among people caught unawares.

Daylight Saving Time begins on Sunday, when clocks will jump instantly from 2 a.m. to 3 a.m.

And if that shift seems somewhat arbitrary, a new map created by math blogger Stefano Maggiolo sheds new light on how arbitrary our conventions of time really are, showing graphically how out of sync the clock is with the real solar day.

"A few years ago I went to Spain for the first time, and like many I was surprised by how late is dinner," Maggiolo writes on his blog. "The first night I dined almost alone in a restaurant at 8 p.m., going away just as people were starting to come in. Of course this can be mostly explained by cultural reasons, but the clearly later-than-usual summer sunsets must also have played a role in shaping the Spanish days."

Maggiolo, an engineer at Google, color-coded a map of the world, showing locations where the clock is behind the solar day in red and places where it is ahead of the solar day in green. The more ahead or behind, the deeper the color.

More than70 countries now observe Daylight Saving Time, but the beginning and ending dates often differ from the U.S., which has itself changed the schedule a number of times over the years.

The Energy Policy Act of 2005 extended the dates of Daylight Saving Time by about a month to its current schedule in 2007, starting on the second Sunday in March and ending on the first Sunday in November.

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Some states in the U.S. do not observe DST, including Hawaii and most of Arizona.

And if you're mourning the loss of that hour on Sunday, don't fret - it isn't gone forever. We get it back when Daylight Saving Time ends on Nov. 2.