The exchange of moisture and heat between the land and the atmosphere is an area of major uncertainty in different fields of environmental research including global problems such as climate change and more local and regional studies such as the influence of changes of the landscape on the microclimate. With the goal of developing an improved representation of land-atmosphere exchange, a numerical soil moisture and heat (NSSMH) transfer model was developed that uses atmospheric conditions as the primary forcing to calculate heat fluxes between the soil and the overlying air. The model calculates vapor and liquid moisture transport as well as sensible heat transfer. In several tests the code was shown to be a useful tool for understanding the nature of the surface exchange phenomena. Among these, it was shown that during the afternoon when the soil surface is being heated by the sun, water vapor inside the soil column is flowing both downwards and upwards.