Equation (2) shows that fusion enthalpy comprises two contributions: one related to the vapor pressure of the component and the other related to the sublimation pressure
. Therefore, the limits of the aplicability of the method depend on the limits on these two quantities.
The sublimation pressure is calculated from the IAPWS-08 (IAPWS 2008) sublimation pressure equation [p.sub.sub.sup.08] (T).
The sublimation temperature ([T.sub.sub.sup.08]) is calculated for given pressure p by solving iteratively the sublimation pressure equation (Equation 8) in terms of [T.sub.sub.sup.08] = T.
For temperatures T [less than or equal to] 273.75 K, [p.sub.w,s] = [p.sub.sub.sup.08] (T) is the sublimation pressure from Equation 8 of IAPWS-08 (IAPWS 2008).
Whatever is freeing the dust -- be it mere sublimation of the ice that traps it, electrostatic "levitation," or sudden bursts produced by the exposure of ices whose sublimation pressure
is lower than that of water ice -- the expansion of the area covered by dust provides a conspicuous signature.