The Nature of Physical Geography

THE EARTH HAS A WEALTH of intriguing features, from dramatic mountains to intricate coastlines and deep ocean trenches, from lush, beautiful valleys to huge areas of sparsely vegetated sand dunes. Above the surface is an active, ever-changing atmosphere with clouds, storms, and variable winds. Occupying all these environments is life. In this chapter and book, we examine the main concepts of physical geography, along with the tools and methods that physical geographers use to study the landscapes, oceans, climate, weather, and ecology of Earth.

The large globe spanning these two pages is a computer-generated representation of Earth, using data collected by several satellites. On land, brown colors depict areas of rock, sand, and soil, whereas green areas have a more dense covering of trees, bushes, and other vegetation. Oceans and lakes are colored blue, with greenish blue showing places where the water is shallow or where it contains mud derived from the land. Superimposed on Earth's surface are light-colored clouds observed by a different satellite, one designed to observe weather systems.

What are all the things you can observe from this portrait of our planet? What questions arise from your observations?

Natural hazards, including volcanic eruptions and earthquakes, are a major concern in many parts of the world. In the Greek Island of Santorini, people live on the remains of a large volcano that was mostly destroyed in a huge eruption 3,600 years ago, an eruption that probably gave rise to the story of Atlantis.

What occurs during a volcanic eruption? Do all volcanoes erupt in the same way, and how can we recognize a volcano in the landscape?

The Sahara Desert, on the opposite side of the Mediterranean Sea from Greece, has a very different climate. Here, a very dry environment results, forming huge areas covered by sand dunes with almost no vegetation. What do the features of the landscape — the landforms — tell us about the surface processes that are forming and affecting the scenery?

What causes different regions to have different climates, some that are hot and dry, and others that are cold and wet? Is the climate of the Sahara somehow related to the relative lack of clouds over this area, as shown on the globe?

Most questions that arise from observing this globe are within the domain of physical geography. Physical geography deals with the landforms and processes on Earth's surface, the character and processes in oceans and other bodies of water, atmospheric processes that cause weather and climate, and how these various aspects affect life, and much more.

Water is the most important resource on the planet, and Earth's temperatures allow water to occur in three states of matter — solid, liquid, and vapor. Examine this photograph and identify all the ways in which water is expressed on the surface and in the atmosphere. Is some water likely present but not visible? Geographers are concerned with where resources are, what causes a resource to be where it is, how to locate more of this resource, and how to reconcile the inevitable economic, environmental, and cultural trade-offs involved in using a resource.

How does water occur in the atmosphere, how is its presence expressed, and what is its role in severe weather? How does water occur and move on Earth's surface and what landforms result from running water?

Oceans cover three-fourths of Earth's surface. Ocean temperatures, currents, and salinity all play a major role in global weather, climate, and the livability of places, even for those far from the coast. The oceans and nearby lands represent important habitats for plants and animals, which can be greatly impacted by human activities.

How do satellites help us measure the temperature, salinity, and motion of the oceans, and how do changes in any of these factors affect plants and animals that live in or near the sea?


The Ancient and Modern Discipline of Geography

Geographers seek to understand the Earth. They do this by formulating important and testable questions about the Earth, employing principles from both the natural and social sciences. Geographers use these principles to portray features of the Earth using maps and technologically intensive tools and techniques that are distinctly geographical. Geographers synthesize the diverse information revealed by these tools to investigate the interface between the natural and human environment. The study of the spatial distribution of natural features and processes occurring near Earth's surface, especially as they affect, and are affected by, humans, is physical geography.

The ancient discipline of geography is especially relevant in our modern world, partly because of the increasing recognition that many problems confronting society involve complex interactions between natural and human dimensions. Such problems include the complex spatial distribution and depletion of natural resources; contamination of air, water, and soils; susceptibility of areas to natural disasters, including earthquakes, volcanic eruptions, flooding, and landslides; formation of and damage caused by hurricanes, tornadoes, and other severe weather; the current and future challenges of global environmental change, and the environmental implications of globalization. The topics and questions introduced on these pages provide a small sample of the aspects investigated by physical geographers and are discussed more fully in the rest of the book. We hope you enjoy the journey learning about our fascinating planet.