How Many Minutes of Daylight Do People Gain Each Day?
Following the winter solstice, which has the fewest hours of daylight each year and usually occurs on or around December 21, people in the Northern Hemisphere gain roughly 90 seconds to two minutes of daylight each day through January. That number increases to 2.5 minutes of sunlight per day in February.
We continue to gain small increments of sunlight each day, past the vernal equinox in March when the lengths of night and day are almost equal. The daily increases last until the summer solstice in June, which marks the longest day of the year. Following this, the amount of daylight slowly begins to decrease again until winter.
Increasing and Decreasing Sunlight
The amount of daylight varies in predictable patterns throughout the year. On one end of the spectrum, solstices in June and December mean the longest and shortest days in the Northern Hemisphere, respectively. During equinoxes, the day and night are both around 12 hours long. You likely won’t notice the amount of daylight change from day to day. However, equinoxes can result in a more pronounced change in the amount of sunlight you notice that we get per day. Most of these changes result in a daily gain or loss of 90 seconds to 2.5 minutes depending on where you are within your time zone, although the range can stretch up to three minutes.
Understanding the Summer and Winter Solstices
During the winter solstice, the pole of the Earth's axis is farthest from the sun, so the Northern Hemisphere is tilting away from the sun at this time of year. During this time, the Earth is positioned in such a way in orbit that the sun remains below the North Pole horizon. This means we receive less direct sunlight because the sun is lower in the sky, not directly overhead, and the days are shorter with longer nights.
At this point, every part of the planet north of the equator experiences fewer than 12 hours of daylight, while any place south of the equator has over 12 hours of light per day. Once the winter solstice passes, in the Northern Hemisphere, the days gradually start to get longer while the nights become shorter.
The summer solstice occurs on or around June 20 and is the longest day of the year for those in the Northern Hemisphere. The opposite is true in the Southern Hemisphere, where the June solstice marks the beginning of winter, with shorter days and longer nights. During the summer solstice, Earth's North Pole tilts more towards the sun. The sun follows a high arc across the sky, and shadows are at their shortest around noon in each time zone.
How Do Equinoxes Affect Sunlight?
An equinox is a day when there's an equal amount of light during day and night. Unlike the summer and winter solstices, an equinox produces similar results around the planet. As with solstices, there are two equinoxes during the year. The spring equinox occurs around March 20, while the autumnal equinox takes place around September 22. For those in the Northern Hemisphere, the spring equinox typically marks the shift from winter to spring, and the autumn equinox marks the transition from summer to fall.
Daylight Saving Time
Daylight saving time (DST) is another way that we "gain" daylight — meaning we might perceive we’re getting more — even though the number of minutes of light per day still changes at its consistent rate. DST occurs twice a year, with us setting our clocks either an hour later in spring or an hour earlier in autumn. In both cases, the idea is that we adjust time so the sun rises and sets later to provide an extra hour of sunlight later in the day. In addition to increasing productivity, this extra hour of sunlight may lower the risk of traffic accidents and even lead to a lower crime rate by reducing the number of evening robberies that take place.