In certain circumstances, one may measure surface tensions that are different from the equilibrium value. Such a surface tension is called the dynamic surface (or interfacial) tension (\(\gamma ^{\text{dyn}}\) or \(\sigma ^{\mathrm{dyn}}\)). The equilibrium value is then called the static surface (or interfacial) tension (\(\gamma ^{\text{st}}\) or \(\sigma ^{\mathrm{st}}\)). The modifying signs may be omitted if there is no danger of ambiguity.