Lines of equal value were drawn for the exposure factors in an area around the top of the towers, again using double logarithmic scales to show detail near and far. The enhancement at the tip is of the order of 10,000 for the sharp point but only 100 for the blunt point. The sharp point goes into corona in low fields and just immediately around the tip, the blunt point goes into corona only in high fields, but out to greater distances from the tower. These were correlated to changes in electric fields caused by lightning discharges. Results of this work confirm earlier theoretical models about sharp vs blunt rod behavior.
Sharp rods are poorer receptors for lightning than blunt rods.
W. Rison, et al, Proceddings 24th ICLP, Birmingham UK, Sept 14, 1998.