This famous quote by geographer Yi-Fu Tuan summarizes the branch of geography known as physical geography.
The discipline of geography is divided into two major branches: 1) physical geography and 2) cultural or human geography. Physical geography encompasses the geographic tradition known as the Earth Sciences Tradition. Physical geographers look at the landscapes, surface processes, and climate of the earth - all of the activity found in the four spheres (the atmosphere, hydrosphere, biosphere, and lithosphere) of our planet.
Physical geography consists of many diverse elements. These include: the study of the earth's interaction with the sun, seasons, the composition of the atmosphere, atmospheric pressure and wind, storms and climatic disturbances, climate zones, microclimates, hydrologic cycle, soils, rivers and streams, flora and fauna, weathering, erosion, natural hazards, deserts, glaciers and ice sheets, coastal terrain, ecosystems, and so very much more.
Knowing about the physical geography of the planet is important for every serious student of the planet because the natural processes of the earth (which is what the study of physical geography encompasses) affect the distribution of resources, the conditions of human settlement, and have resulted in a plethora of varied impacts to human populations throughout the millennia. Since the earth is the only home to humans, by studying our planet, we humans and residents of the planet earth can be better informed to help take care of our only home.