Emissions of heat and moisture from human activities in the urban environment can lead to significant impacts on the urban climate. Some studies have shown anthropogenic sensible heat to elevate ambient air temperatures by several degrees Celsius. While recent research has demonstrated that accurate representation of anthropogenic heat is a crucial aspect of modeling the urban climate there has been relatively little attention paid to the role that anthropogenic moisture plays. Anthropogenic moisture emissions come from several key sources. For every liter of automotive fuel burned, approximately 1kg of water vapor is formed as part of the combustion products. The heavy reliance on combustion fuels in the industrial sector also leads to significant emissions of water vapor. In the building sector, moisture emissions result from combustion of heating fuels and from evaporative cooling equipment. Depending upon location and climate there is a varying level of penetration of evaporative coolers in the residential market. In commercial buildings, however, cooling towers are relatively common, especially in larger buildings. These cooling towers often meet up to 80% of the building's cooling load through latent heating, with the remaining load being met through sensible heating.

This paper takes a detailed look at the spatial and temporal distribution of total anthropogenic heating in several cities. It explores the partitioning of this heating between latent and sensible loads. It then concludes with analysis of a small suite of mesoscale atmospheric model runs to explore the role of anthropogenic heat and moisture emissions. These runs include a control simulation in which no anthropogenic latent or sensible heating is included; a simulation with only latent heating; one with only sensible heating; and a final simulation with both latent and sensible anthropogenic heating. Analysis of these runs focuses on the implications of anthropogenic heat and moisture for urban air temperatures, humidity levels, and human thermal comfort. Implications for convective thunderstorm development are also discussed.