Physical geography is the study of Earth's processes and features, including the human environment. It has specialties like meteorology, climatology, and geomorphology. The main themes of geography are location, characteristics of places, spatial distribution and patterns, and human-environment interactions. Science follows a process of making observations, proposing hypotheses, testing them, and either accepting or reformulating theories based on the results. The major spheres that make up Earth are the atmosphere, lithosphere, hydrosphere, and biosphere, which all interact with each other.