Latin America's geographical location and geomorphology contribute to its large variety of climates, ranging from hyper-arid desert climates to humid tropical forest climates. The regional climate distribution is defined by interactions among the predominant atmospheric circulation patterns and the region's topographical features, radiation budgets, and heat and water balances-which, in turn, depend on the vast range of soil/vegetation types of the region. The extensive central portion of Latin America is characterized largely by humid, tropical conditions; important areas (e.g., in Brazil) are subject to drought, floods, and freezes. Atmospheric circulation and ocean currents are causal factors of extensive deserts in northern Mexico, Peru, Bolivia, Chile, and Argentina.