The darkness of night thrusts the subject visually forward.  In Low Key pictures detail is in shadow.

See also how expert photgraphers portray Night 1, Night 2, Night 3, Beginner Night, Beginner Night 2, Builidings at Night, Light and Dark, Low Key, Black Backdrop, Low Key 2007, Black Backdrop 2007, Black on Black.
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Boy Scout Troop 174, Yorktown, NY.  Scouting Photography Pages at  http://troop174.info