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.
December Solstice: Shortest day of the year in the Northern Hemisphere. The December solstice is on either December 20, 21, 22 or 23. It is called Winter Solstice in the Northern Hemisphere, where it is the shortest day of the year. In the Southern Hemisphere, it is the Summer Solstice and the longest day of the year. The North Pole is tilted furthest from the Sun. The North Pole is tilted furthest away from the Sun at the December solstice.