Dear Tom,
By how many minutes and/or seconds per day does the amount of daylight increase in the Chicago area in the week after the winter solstice?
— Jon Kartman, Mundelein
Dear John,
The United States Naval Observatory annual daylight table for Chicago shows minimum daylight of nine hours and eight minutes spanning seven days from Dec. 18-24, decreasing daily by 12 seconds or less before the solstice and increasing by a similar amount after it. From Dec. 25-27, daylight increases back to nine hours and nine minutes and then to nine hours and 11 minutes by Dec. 31. Beyond Jan. 11, the increase accelerates to two minutes a day and then to three minutes a day by mid-February. In May, the increase slows to two minutes a day and then to a minute a day as the June summer solstice approaches, finally peaking at 15 hours and 13 minutes in the June 16-26 period.