Summary of the
This chapter introduces the student to
the importance of matter and energy in the study of
Physical Geography. All physical objects in our universe
are constructed of matter. At the atomic level, matter
can be made up of one single element type or it can
be the chemical combination of a number of different
elements called compounds. Life can synthesize and
organize matter into complex organic molecules and
structures like cells and organs.
Einstein suggested that matter and energy
are related to each other at the atomic level. Energy
and matter are also associated to each other at much
larger scales of nature. The laws of thermodynamics
describe some of the associations between energy and
matter as they relate to the Universe.
Energy can be defined as the capacity
for doing work. It exists in many different forms and
can be transferred from one place to another by the
processes of conduction, convection and radiation.
Some of the more important forms of energy include:
heat energy, electromagnetic radiation, and chemical
energy. Heat is defined as energy in the process of
being transferred from one object to another because
of the temperature difference between them. Temperature
variation across space can be generated by a number
of different processes. A few physical laws can describe
the nature of electromagnetic radiation. One of these
laws suggests that any object above the temperature
of absolute zero emits radiation to its surrounding
environment. Another law suggests the quantity and
quality of the radiation emitted is determined by the
radiating body's temperature. Chemical energy comes
in many different forms. However, the most important
form, as it relates to this course, is the chemical
energy generated by life in various types of organic
molecules through the process of photosynthesis.
The Sun is the major source of energy
for biotic and abiotic systems on the Earth. The Sun
creates large amounts of electromagnetic radiation
through atomic fusion. This solar energy travels through
space decreasing in intensity with distance from the
Sun. Only a small percentage of this energy emitted
by the Sun is intercepted and received by the Earth.
The amount of energy available at the various locations
on the Earth's surface is controlled by a number of
geometric and astronomical factors.
List of Key Terms
Zero, Advection, Algae, Amino
of Incidence, Aphelion, Atom, Atomic
Energy, Autotroph, Autumnal
Calorie, Carbohydrate, Cell, Cellulose, Celsius
Energy, Chlorophyll, Compound, Conduction, Convection, Convection
Waves, Electron, Element, Energy, Entropy, Enzyme, Equinox,
Heat, Light, Lipid,
Mass, Matter, Mean
Solar Day, Metabolism, Molecule,
Primary Productivity, Neutron, Newton, Nuclear
Perihelion, Photosphere, Photosynthesis, Plane
of the Ecliptic, Polar
Energy, Protein, Proton, Protozoa,
Noon, Solstice, Specific
Heat, Spectrum, Speed
of Light, Spring
Atmospheric Pressure, Stefan-Boltzmann
Solstice, Sun, System,
Problems, and Exercises
(1). What is energy?
(2). What forms does energy come in?
(3). How the three mechanisms of conduction,
convection and radiation move energy from one place
(4). Outline the three laws of thermodynamics.
(5). What is radiation? How is it created?
What factors determine its quantity and quality?
(6). Verbally define the Stefan-Boltzmann
Law. What does it describe?
(7). Verbally define the Wien's Law.
What does it describe?
(8). Why does the intensity of electromagnetic
radiation decline as it travels away from its source?
(9). How does the Sun create the energy
that drives most systems on the Earth?
(10). How does the tilt of the Earth's
axis influence the annual solar insolation received
at a site located at 50 degrees North latitude?
(11). What influence does Earth rotation
have on solar insolation received at the equator?
(12). How does angle of incidence control
the intensity of solar radiation received at the
(13). How are photosynthesis and respiration
used by life to create and release chemical energy?