Final answer:
The four great earth realms in physical geography are the atmosphere, hydrosphere, lithosphere, and biosphere. These represent the gaseous, water, surface and life aspects of our planet, respectively.
Step-by-step explanation:
The four great earth realms that are studied in physical geography include the atmosphere, the hydrosphere, the lithosphere, and the biosphere. The atmosphere refers to the layer of gases that surrounds the Earth. The hydrosphere encompasses all of Earth's water, including the oceans, seas, rivers, and glaciers. The lithosphere refers to the Earth's surface crust and upper mantle, while the biosphere is the sphere of life, inclusive of all living organisms.
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