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Tropical montane cloud forests (TMCFs) depend on predictable, frequent, and prolonged immersion in cloud. Clearing upwind lowland forest alters surface energy budgets in ways that influence dry season cloud fields and thus the TMCF environment. Landsat and Geostationary Operational Environmental Satellite imagery show that deforested areas of Costa Rica's Caribbean lowlands remain relatively cloud-free when forested regions have well-developed dry season cumulus cloud fields. Further, regional atmospheric simulations show that cloud base heights are higher over pasture than over tropical forest areas under reasonable dry season conditions. These results suggest that land use in tropical lowlands has serious impacts on ecosystems in adjacent mountains.

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Abstract. This paper uses published work to demonstrate the link between surface moisture and heat fluxes and cumulus convective rainfall. The Earth's surface role with respect to the surface energy and moisture budgets is examined. Changes in land-surface properties are shown to influence the heat and moisture fluxes within the planetary boundary layer, convective available potential energy, and other measures of the deep cumulus cloud activity. The spatial structure of the surface heating, as influenced by landscape patterning, produces focused regions for deep cumulonimbus convection. In the tropics, and during midlatitude summers, deep cumulus convection has apparently been significantly altered as a result of landscape changes. These alterations in cumulus convection teleconnect to higher latitudes, which significantly alters the weather in those regions. The effect of tropical deforestation is most clearly defined in the winter hemisphere. In the context of climate, landscape processes are shown to be as much a part of the climate system as are atmospheric processes. INTRODUCTIONThe fuel for thunderstorms is heat energy. This heat energy can be derived from sensible heating at the Earth's surface and from the release of heat as water vapor condenses or freezes. To develop into the characteristic cauliflower form of a thunderstorm cloud, the cloud air must be warmer than the surrounding air, such that the cloud air accelerates upward in a turbulent, bubbly form. The cauliflower-shaped cloud terminates its upward ascent at strong temperature inversions in the troposphere or, more commonly, at the tropopause, which separates the troposphere from the stratosphere. The interaction between the Earth's surface and the atmosphere is therefore critically important with respect to the development of cumulus convective rainfall. Weather forecasters use a variety of parameters, derived from the vertical profile of thermodynamic variables in the atmosphere, to assess the potential for such rainfall. These parameters are introduced in Appendix A and will be referred to within the text. Surface EffectsThe surface energy and moisture budgets for bare and vegetated soils during typical thunderstorm weather conditions (snow and ice effects are not considered in this discussion) are schematically illustrated in Figures 1 and 2. These surface budgets can be written as RN = QG + H + L(E + T)(1)

This article summarizes the changes in landscape structure because of human land management over the last several centuries, and using observed and modeled data, documents how these changes have altered biogeophysical and biogeochemical surface fluxes on the local, mesoscale, and regional scales. Remaining research issues are presented including whether these landscape changes alter large-scale atmospheric circulation patterns far from where the land use and land cover changes occur. We conclude that existing climate assessments have not yet adequately factored in this climate forcing. For those regions that have undergone intensive human landscape change, or would undergo intensive change in the future, we conclude that the failure to factor in this forcing risks a misalignment of investment in climate mitigation and adaptation. (C) 2011 John Wiley & Sons, Ltd