Sentence:  In free burning electric arcs , for instance , approximately 90 % of the total arc power is transferred to the anode giving rise to local heat fluxes in excess of **f as measured by the authors - the exact value depending on the arc <WSD>atmosphere</WSD> . 
Meaning of the word marked with <WSD> tags:  a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade