A blood blister forms when skin and small blood vessels are damaged without breaking the skin. Trapped beneath the skin surface is some blood and skin fluid. Blood blisters are commonly caused by accidents in which the skin is pinched by a tool or a heavy weight, or they may occur from constant rubbing back and forth.
1 Sunshine hours in Chicago, Illinois range between 3:42 per day in December & 10:14 for each day in July. 2  The longest day of the year is 15:02 long and the shortest day is 8:57 long.  The longest day is 6:04 longer than the shortest day.
The length of the shortest day of the year depends on the location. In the United States, some areas get less than 4 hours of sunshine on the shortest day. In places like Washington and New York, the shortest day lasts for up to 9 1/2 hours.