New column simulations for the Viking landers: Winds, fog, frost, adsorption?

•Moist summer column simulations are presented for the Viking lander sites.•Observed diurnal winds and temperatures are adequately reproduced.•Adsorption in the evening and frost from midnight deplete near-surface water vapor.•Fog is formed at night, increasing optical depth as observed.•Porosity of 22% conserves PWC from sol to sol at both sites.