Geoscience Reference
In-Depth Information
geography examines the spatial variation within these spheres,
how natural systems work within them, the observable out-
comes in each, and the manner in which components flow
from one sphere to another.
Physical geography can be a descriptive discipline that
simply characterizes the nature of the Earth's spheres in spe-
cific regions. A simple example of such a descriptive focus
would be to acknowledge that the western part of the United
States is mountainous, whereas the central part of the country
consists mostly of relatively level plains. Physical geography is
also a science because research is conducted within the frame-
work of the scientific method, which is the systematic pursuit of
knowledge through the recognition of a problem, the formulation
of hypotheses, and the testing of hypotheses through the collec-
tion of data by measurement, observation, and experiment. The
conclusions derived from the systematic application of the scien-
tific method contribute to the formulation of scientific theories
and laws that explain how Earth functions.
A simple example of using the scientific method in physi-
cal geography would be to test the hypothesis that water
in streams within a certain region is acidic. This hypoth-
esis would best be tested by collecting water samples from
a number of streams and conducting chemical analyses on
them to determine their acid levels. If high acid levels were
indeed obtained, then an effort would be made to explain why
that pattern occurred. In addition to the understanding produced
in these kinds of analyses, physical geographers also test hypoth-
eses about all sorts of natural phenomena by collecting informa-
tion from the atmosphere, rocks, soils, ice cores, satellite images,
the Earth's magnetic field, and even other planets (Figure 1.6).
For these investigations to occur, it is essential that scientists
understand physical laws and have the ability to mathematically
analyze and compare them.
Atmosphere
Hydrosphere
Earth
Lithosphere
Biosphere
Figure 1.5 The four Earth spheres.
Each sphere encompasses
a major component of the Earth's natural environment.
system in this sphere is the way in which water, miner-
als, and organic matter flow in the outermost layer of the
Earth to form soil. This sphere provides the habitat and
nutrients for many life-forms.
3.
Hydrosphere
—The hydrosphere is the part of Earth where
water, in all its forms (solid ice, liquid water, and gaseous
water vapor), flows and is stored. This sphere is absolutely
critical to life and is one with which humans regularly
interact—for example, through irrigation and navigation.
4.
Biosphere
—The biosphere is the living portion of
Earth and includes all the plants and animals (includ-
ing humans) on the planet. Various components of this
sphere regularly flow from one place to another, both on a
seasonal basis and through human intervention. Humans
interact with this sphere in a wide variety of ways, with
agriculture being an obvious example.
Organization of This Topic
The chapters in this topic are organized to provide you with a
good understanding of the fundamental concepts associated with
physical geography. They contain information that ranges in scale
from global to local, which will allow you to better grasp your
place both in the world and even in your neighborhood. Chapter 2
focuses on the various kinds of tools that geographers use in their
work, such as maps, remote sensing, and geographical informa-
tion systems. Chapters 3 through 5 examine our relationship with
the Sun (Chapter 3), the way we receive solar radiation (Chapter
4), and how those interactions relate to temperature (Chapter 5).
The processes discussed in these chapters will prepare you for
the topics that will be covered in the rest of the topic. Chapters
6 through 9 revolve around the atmosphere, including the way
that air circulates within it (Chapter 6), precipitation processes
(Chapter 7), weather systems (Chapter 8), and global climate pat-
terns (Chapter 9). The text then examines the influence of the
atmosphere and how it interacts with Earth's other spheres by fo-
cusing on plant geography in Chapter 10 and soils in Chapter 11.
Chapters 12 through 19 deal mainly with the lithosphere and
hydrosphere. Chapter 12 describes the Earth's internal structure,
These four spheres overlap to form the natural environment that
makes Earth a unique place within our solar system. Physical
Lithosphere
A layer of solid, brittle rock that comprises the
outer 70 km (44 mi) of Earth.
Hydrosphere
The part of Earth where water, in all its forms,
flows and is stored.
Biosphere
The portion of Earth and its atmosphere that sup-
ports life.
