Form factor is the ratio of a building's total surface area (the walls, roof and ground floor) to its treated floor area. (passivehouseplus.ie)
That seemed to imply that particles in the disk had an unexpectedly low total surface area — as they would if the disks contained particles as large as a few centimeters across, co-author Henry Throop says. (sciencemag.org)
Lake Turkana National Parks are constituted of Sibiloi National Park, the South Island and the Central Island National Parks, covering a total area of 161,485 hectares located within the Lake Turkana basin whose total surface area is 7 million ha. (whc.unesco.org)