The effect of surface heating and cooling on the structure and evolution of the surface front that develops in the finite-amplitude Eady wave is investigated. Spatially uniform short-wave radiative heating of the surface is weakly frontolytic, although it appears this result may be sensitive to the way in which the boundarylayer turbulence is parametrized. The cross-front potential temperature gradient is weakened principally by the differential heating produced by horizontal variations in the depth of the mixed layer, and to a smaller extent by horizontal variations in the surface sensible heat flux. The direct effect of enhanced daytime turbulent stresses is to retard the winds in the boundary layer, reducing the convergence in the cross-front plane, while the indirect effect is to produce a strong cross-isobaric flow towards the trough, thereby increasing the convergence. The net effect is to reduce the rate of frontogenesis near the surface front. During the day the front is oriented vertically in the boundary layer because of the strong mixing. Nocturnal cooling through long-Wave radiative emission from the surface is strongly frontogenetic. At night, as the turbulence decays in the trough ahead of the surface front, air parcels accelerate down the pressure gradient towards the centre of the trough, producing low-level cross-front surges on both sides of the trough axis. This enhanced nocturnal convergence rapidly strengthens the cross-front potential temperature gradient and tilts the front westward with height. Such nocturnal frontogenesis is especially intense when it follows strong daytime turbulent mixing.
