Winnipeg nears spring equinox with equal day and night

​The northern hemisphere is nearing the spring equinox, which is when there are equal parts of day and night.

Sunrise and sunset at 7:37 and 7:35 respectively but spring equinox not until Saturday

​The northern hemisphere is nearing the spring equinox, which is when there are equal parts of day and night.

The northern hemisphere is nearing the spring equinox, which is when there are equal parts of day and night.

It's scheduled to fall on 11:30 p.m. Saturday, but on Thursday, Winnipeg's sunrise and sunset times marked almost exact day and night.

The sunrise time on Thursday was 7:37 a.m. and the sunset time was 7:36 p.m.

So why will it take until Saturday for the official vernal equinox?

"At the equinox in the spring and fall, the geometric centre of the sun is above the horizon for 12 hours, and in turn, below the horizon for the same length of time — equal day and night," CBC Meteorologist John Sauder said. "However, sunrise is defined as the moment the upper edge of the sun's disc becomes visible above the horizon. That's different than the centre of the sun."

Sauder explained it takes several minutes for the sun to fully rise and set. Those minutes are added onto daylight time and subtracted from night.

"The equinox day is several minutes longer than 12 hours," said Sauder.

The spring or "vernal" equinox is meant to signal the start of spring, and those days where there are actual equal amounts of day and night are called equiluxes. 

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