Abstract: The interactions between wetlands and the hydrological cycle are well known with increasing attention being focused on environmental flows and the links between surface and ground water. The relationships between the climate and the water regime in wetlands has also been increasingly investigated, including from a methodological side given the uncertainty and variability associated with many past measurements. As there is less clarity about the effect of weather and climate, these terms are explained below within the context of global climate change and the role of wetlands. The chapter provides terms and definitions to help clarify the terminology used to describe interplay between atmosphere and land surface. Main fluxes of solar energy in wetlands and on dry land surface are outlined.