This chapter explores the dynamic processes governing the Earth’s thermal characteristics and their impact on environmental conditions. It delves into the fundamental properties influencing heat transfer on the Earth’s surface and atmosphere, including albedo, thermal conductivity, specific heat, and permeability. This chapter examines how land and ocean surfaces heat and cool, addressing the influence of soil moisture, vegetation, and snow cover on diurnal and annual temperature fluctuations. It further investigates the depth variations of soil temperature and the impact of different substrates and climatic conditions. The interactions between heat balance, radiation, and surface characteristics, as well as the role of ocean properties such as salinity in thermal dynamics, are analyzed in detail. Through these discussions, this chapter highlights the importance of Earth’s thermal system in shaping local and global climate patterns and its implications for environmental and ecological systems.