As I have mentioned before, I see Geography as a series of relationships and as we look back through the history of Geography we see three main areas that we can use as umbrellas for the broad aspects of Geography: cartography, human geography and physical geography. Physical Geography covers the relationships within the environment around us, a broad area to be sure, but an important one in our daily lives.
LetÃ¢â‚¬â„¢s begin with the top and work our way down. Climatology and meteorology look at the long term and short term relationships between the atmosphere and the earth which yields weather and climate. Toss in the human effects and you also have issues regarding global warming and broader climate change. Taking the next step down, we look at biogeography, which includes the impact of fire and insects on forests, the depletion of the rain forests impacting the native habitat of indigenous species, or migration of species due to human encroachment. Oceanography is closely related to traditional biogeography and includes research into species migration and depletion, but as well as the impact of greenhouse gases on the aquatic wildlife that feed of CO2 and how that impact flows up the food chain.
Geomorphology is the basis of much of Physical Geography and focuses on the genesis of landscapes through natural and cultural means. In river valleys we can discuss alluvial deposits, in arid regions Aeolian effects, erosion, siltation, etc. From the movement of glaciers to how the resulting landforms are used today, geomorphology is the groundwork of a great deal of Geography.
These research areas represent some of the main themes of Physical Geography, but by no means all of them. To find out more, you may want to check out some of the following links