Physical Geography

The Earth is a complex physical system with a myriad of interconnected and interdependent parts. The Earth system and it’s many subsystems are for humans, and millions of other species, a delicate life support system that shelters us from the unforgiving and lifeless  vacuum of outer space. Physical geographers and others in the physical and natural sciences study these systems and processes not only to understand them, but to protect life from the havoc changes in any one of Earth physical systems — whether induced by humans or otherwise — can have on our society and the planet’s natural ecosystems. Physical geography may be described as the study of the Earth’s physical features and systems, their distributions, and the spatial relationships among them. Other major branches of geography include human geography and regional geography.

What do physical geographers study?

Geographers in general are interested in spatial patterns and relationships, and thus physical geographers study distributions of physical features and the spatial relationships among them. Strong tropical storms, for example, form over warm seawater, which has a distinct spatial pattern over the Earth’s surface. Storms tend to track along with the prevailing wind patterns, another spatially-explicit phenomena. And, of course, a tropical storm itself rotates in a predictable manner due to the Earth’s rotation, and wind speeds are directly correlated with distance from the storm’s eye wall. The very formation of a tropical storm (also know as a hurricane, cyclone, or typhoon) is a spatially-explicit process, with air converging and rising around a low pressure center in the lower atmosphere. Each of these spatial patterns are of interest to geographers, and most physical/natural systems and phenomena on Earth exhibit clear geographic patterns over space and time.

hurricane harvey satellite image
Tropical storms such as Hurricane Harvey, which struck the Texas coast in Sep. 2017, form and move in distinct geographic patterns that have important implications for people. Credit: NOAA.

Physical geographers study each of Earth’s four major sub-systems: the atmosphere, the lithosphere (or geosphere), the hydrosphere, and the biosphere. Spatial movements of air in the atmosphere give rise to patterns of weather and climate observed at and near the Earth’s surface. The lithosphere includes the solid Earth — generally the ground beneath your feet including any soil and rock, and the various processes causing landscapes to change (i.e., gemorphology). There is some overlap in this realm with the field of geology. Physical geography normally deals with very shallow or surface-level processes while geology tackles subsurface structures and phenomena such as faulting. The hydrosphere refers to all the water circulating around the globe, including all the water in lakes and rivers (surface water), in ice and glaciers, under the ground, and in the atmosphere (i.e., water vapor, clouds, precipitation, etc.).

Major Sub-fields of Physical Geography

Geomorphology, the study of the physical landscape, is one of the most active sub-fields of physical geography. Geomorphologists aim to understand how and why landscapes evolve the way they do; how flood plains develop, how different soils form, and how mountains and valleys are created, to name just a few examples. These patterns and the processes that give rise to them are often of considerable interest to people. It’s useful to know how certain slopes and substrates are going to react in varying conditions, which might impact how a building or other engineered structure is built.

Other substantial sub-fields of physical geography include meteorology and climatology, hydrology (the study of water across the landscape), pedology (the study of soils specifically), and biogeography (the study of the spatial distributions and flows of living organisms). Meteorology and climatology have taken on new importance in the era of climate change. Physical geographers work closely with climatologists to predict changes at a variety of scales related to rising carbon dioxide levels and temperatures in the atmosphere and hydrosphere. The potential for stronger tropical storms and sea level rise have great implications for coastal populations, and an understanding of the geography of these changes is key to preparation and hazard mitigation. The field of emergency management relies on data and conclusions provided by physical geographers.

As the climate changes, there will be significant implications for the Earth’s ecosystems and biomes. Living organisms and entire ecosystems are likely to migrate if possible to more hospitable areas as their current habitats change or degrade due to changes in temperature, precipitation, and other atmospheric conditions. Biogeographers are well poised to understand these migrations and other changes to wildlife ranges (the area occupied by a particular species) that have, in some cases, already begun to occur. Biogeographers also study historical distributions of life on Earth, helping to explain current biological patterns and relationships. The presence or lack of certain species, or groups of species, in certain regions of the planet is a product of migration and evolution over space — processes studied by biogeographers.

As with flows of living organisms from place to place, physical geography is also concerned with the flow of nutrients and other physical elements throughout the Earth system. The flow of water from the oceans to the land, and back to the oceans, for example, is known as the water cycle. In this process, water is capable of slowing sculpting the landscape, giving rise to a variety of features studied by physical geographers. Carbon, like water, flows throughout the Earth system, being taken up by plants and animals, stored in their bodies for a time, then eventually released back into the atmosphere or soil. Naturally, this process is known as the carbon cycle. All of the surface cycles are powered by the sun, while tectonic activity underground is driven by the Earth’s own geothermal energy.

Collecting Data

Often, data on the Earth’s physical geography is collected over broad geographical areas using either aircraft (including drones) or satellites. This type of data collection is known as remote sensing, and is a particularly useful tool for both physical and human geographers. This data is frequently imported into a geographic information system, or GIS, for analysis. Several government agencies and organization worldwide collect and distribute remotely sensed data for free, such as the U.S. Geographical Survey (USGS), the U.S.Department of Agriculture, NASA, and the National Oceanic and Atmospheric Administration (NOAA) in the United States. These data have proven invaluable to physical geographers around the world studying climate change, soil erosion, urban development, and other unprecedented changes to our fragile earth system.

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