Unlike most snow-effect photographs, the “snowflakes” in this image seem to have been added to the negative one at a time.
The Minnesota Historical Society owns a cabinet photograph by Greenleaf of costumes from the St. Paul Winter Carnival of 1886; this may be a similar study.
A Carlton J. Greenleaf was listed among the veterans of the 24th Michigan Regiment, which suffered the highest rate of casualties of any Union regiment at Gettysburg. The 24th Michigan was part of the famed “Iron Brigade.”