Days start getting longer after the winter Solstice (Dec. 21).  The length of day increases along a sinusoidal curve, so the fastest changes occur around the vernal equinox (Mar. 21), slowing down and stopping at the summer solstice.

In Milwaukee, on the shortest day of the year, the sunrise time is 7:20 am, and the sunset time is 4:20 pm.  By January 1st, the times are 7:23 am and 4:28 pm respectively.  You really start to notice it staying lighter later by early February when the sun goes down at 5:04 pm.  It's up at 7:07am.  By the vernal equinox, around March 21, the sun up time is 6:53 am and the sun down time is 7:05 pm (Daylight Saving Time).

A solstice is not actually a day, but a moment of a day, the exact moment the sun reaches its highest or lowest point in the sky. The opposite occurs in the Southern Hemisphere.

In the Northern Hemisphere, the longest day of the year occurs on the summer solstice (when the northern pole of earth's axis is tilted toward the sun). The sun is in the highest position in the sky as seen from the North Pole. This occurs between June 20 and 22 each year. Sunrise time is 5:13 am followed by the sunset time at 8:35 pm. The hours of sunlight each day gets progressively shorter each day until the winter solstice (the shortest day of sunlight).

Around the start of fall, the sunrise time is 6:38 am, and the sunset time is 6:51 pm.