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We consider the effects of radio-wave scattering by cool ionized clumps($T\sim 10^4\,$K) in circumgalactic media (CGM). The existence of such clumpsare inferred from intervening quasar absorption systems, but have long beensomething of a theoretical mystery. We consider the implications for compactradio sources of the `fog-like' two-phase model of the circumgalactic mediumrecently proposed by McCourt et al.(2018). In this model, the CGM consists of adiffuse coronal gas ($T\gtrsim 10^6\,$K) in pressure equilibrium with numerous$\lesssim 1\,$pc scale cool clumps or `cloudlets' formed by shattering in acooling instability. The areal filling factor of the cloudlets is expected toexceed unity in $\gtrsim 10^{11.5} M_\odot$ haloes, and the ensuing radio-wavescattering is akin to that caused by turbulence in the Galactic warm ionizedmedium (WIM). If $30\,$per-cent of cosmic baryons are in the CGM, we show thatfor a cool-gas volume fraction of $f_{\rm v}\sim 10^{-3}$, sources at $z_{\rms}\sim 1$ suffer angular broadening by $\sim 15\,\mu$as and temporal broadeningby $\sim 1\,$ms at $\lambda = 30\,$cm, due to scattering by the clumps inintervening CGM. The former prediction will be difficult to test (the angularbroadening will suppress Galactic scintillation only for $<10\,\mu$Jy compactsynchrotron sources). However the latter prediction, of temporal broadening oflocalized fast radio bursts, can constrain the size and mass fraction of coolionized gas clumps as function of halo mass and redshift, and thus provides atest of the model proposed by McCourt et al.(2018).

Radio wave scattering by circumgalactic cool gas clumps