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.
When is the shortest day of the year? The shortest day and the longest night of the year in the Northern Hemisphere occur during winter solstice which is usually observed on december 21st or sometimes on december 22nd UTC (see table 1). In 2016 winter solstice is observed on december 21, exactly at 10:44 UTC.