This statue is pretty abstract and had me and the children scratching our heads trying to make heads or tails of it. The name of the sculpture only made matters of work. Clearly we'd have to go home and read about it. 
Atmosphere And Environment XII was sculpted in 1970 by Louise Nevelson. The sculpture is made of Cor-Ten steel and the base is of granite with plywood support. That's about what I could figure.
A few years ago this sculpture receive some treatment and was rededicated on May 8, 2007. A beautiful spring day formed the ideal backdrop for Louise Nevelson's Atmosphere and Environment XII (1970), which was rededicated on May 8, 2007. The pioneering Cor-Ten steel sculpture was returned to its base outside the west entrance of the Philadelphia Museum of Art after undergoing comprehensive conservation treatment performed by the Museum's conservation department. The Art Association acquired the sculpture in 1972. SOURCE
Atmosphere and Environment XII is a product of the mature style of Louise Nevelson, one of the most influential artists of the decades following World War II. In the late 1950s, Nevelson conceived of wooden collage "environments," wall-like sculptures painted entirely in one color and incorporating a myriad of abstract forms. Her interest in theater influenced both her concept of sculpture-as-environment and her use of vertical structures resembling stage sets. Atmosphere and Environment XII, made of 18,000 pounds of Corten steel, which gradually weathers to form its own patina, consists of six columns of rectangles bolted together. The rectangles contain within them further geometrical shapes, and the entire openwork composition seems to echo the severe landscape of a modern city. After exhibitions in France and New York, the sculpture was purchased by the Fairmount Park Art Association in 1971 and installed at its present site in 1973. Another example of Nevelson's work in Philadelphia is Bicentennial Dawn. (Adapted from Public Art in Philadelphia by Penny Balkin Bach (Temple University Press, Philadelphia, 1992)).
The statues dimension's are" Sculpture: approx. 174 x 123 x 61 in.; Base: approx. 29 x 138 1/2 x 101 in. (18,000 lbs.). Artist's responsible for the statue's creation: Nevelson, Louise, 1899-1988, sculptor, Lippincott, Inc., fabricator, Cold Spring Granite Company, contractor. Cold Spring Granite Company created the granite base.
and now a word from Wikipedia about the artist:
Louise Nevelson (August 23, 1899 – April 17, 1988) was an American sculptor known for her monumental, monochromatic, wooden wall pieces and outdoor sculptures. Born in Czarist Russia, she emigrated with her family to the United States in the early 20th century when she was three years old. Nevelson learned English at school, as she spoke Yiddish at home. By the early 1930s she was attending art classes at the Art Students League of New York, and in 1941 she had her first solo exhibition. A student of Hans Hofmann and Chaim Gross, Nevelson experimented with early conceptual art using found objects, and dabbled in painting and printing before dedicating her lifework to sculpture. Usually created out of wood, her sculptures appear puzzle-like, with multiple intricately cut pieces placed into wall sculptures or independently standing pieces, often 3-D. A figure in the international art scene, Nevelson was showcased at the 31st Venice Biennale. Her work is seen in major collections in museums and corporations. Louise Nevelson remains one of the most important figures in 20th-century American sculpture. SOURCE