Paul Siple (February 2, 1908 – June 15, 1968) was an American polar explorer, geographer, and United States Army officer notable for his participation in multiple Antarctic expeditions and for co‑developing the wind‑chill factor.
Early life and education
Siple was born in Chicago, Illinois, and grew up in New York City. He attended the Boy Scouts of America, where he earned the rank of Eagle Scout. His scouting experience led to his selection as a student participant in the 1939–1941 United States Antarctic Service Expedition (USAS), commonly known as the “Byrd Antarctic Expedition,” under the leadership of Rear Admiral Richard E. Byrd. Siple later earned a Bachelor of Science degree in geography from the University of Pennsylvania and a Ph.D. in geography from the University of Michigan, where his dissertation focused on polar climatology.
Antarctic expeditions
Siple took part in four major Antarctic expeditions:
- United States Antarctic Service Expedition (1939–1941) – Served as a scientific assistant and participated in the establishment of two research stations, East Base and West Base.
- Operation Highjump (1946–1947) – Served as a scientific consultant and chief of the meteorological section.
- U.S. Navy Operation Deep Freeze I (1955–1956) – Acted as a senior scientific adviser.
- U.S. Navy Operation Deep Freeze II (1956–1957) – Continued in a senior advisory role, focusing on glaciological research.
During these missions, Siple conducted extensive field observations on snow, ice, and atmospheric conditions, contributing valuable data to the understanding of polar environments.
Wind‑chill factor
In collaboration with Charles F. Passel, Siple performed a series of experiments in the 1940s to quantify the effect of wind and temperature on human heat loss. Their work led to the formulation of the “wind‑chill index,” a numerical representation of perceived temperature under windy conditions. The original Siple‑Passel wind‑chill equation was later refined and incorporated into weather services worldwide.
Military and academic career
Siple served as a lieutenant colonel in the United States Army Reserve, specializing in meteorology and cold‑region operations. After his Antarctic work, he held teaching and research positions at the Department of Geography, University of Michigan, and later at the Naval Postgraduate School in Monterey, California, where he taught courses on polar science and environmental physiology.
Publications and legacy
Siple authored several scientific papers and the popular book Alone in the Antarctic (1945), documenting his experiences and observations. His contributions to polar science are recognized by the naming of several Antarctic geographical features after him, including the Siple Coast and Siple Ice Shelf. The wind‑chill formula he helped develop remains a standard component of meteorological reporting, though modern formulations differ mathematically from the original equation.
Death
Paul Siple died on June 15, 1968, in Washington, D.C., from a heart attack at the age of 60. He is buried at Arlington National Cemetery.
