Rapid Change in Light

“A lot of research shows that it’s not the quantity of light. It’s the rapid change in light.”

Quick refresher course: Starting with the winter solstice in December—the shortest day of the year—the amount of daylight starts to increase until the summer solstice in June, which is the longest day of the year. The further from the equator, the greater the overall change in length of day.

Aiken points out that the fastest rate of change in daylight occurs around the equinox, the point when there are equal hours of day and night. (This happens twice, around March 20 and September 20.)
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