Page 25 - Laboratory Manual in Physical Geology

Geosphere Forms of Energy
The geosphere is Earth’s rocky body ( FIGURE 1.5 ). The Here are some of the forms of energy that power you and
inner core has a radius of 1196 km and is composed mostly the Earth system around you.
of iron (Fe) in a solid state. The outer core is 2250 km ■ Thermal (heat) energy is the energy of moving or
thick and is composed mostly of iron (Fe) and nickel vibrating atoms in matter related to its temperature.
(Ni) in a liquid state. The mantle is 2900 km thick and is The higher the temperature, the greater the vibration
composed mostly of oxygen (O), silicon (Si), magnesium or motion of its molecules. A hot cup of tea has a
(Mg), and iron (Fe) in a solid state. The crust has an lot of thermal energy, but a cup of iced tea has less
average thickness of about 25 km and is composed mostly thermal energy. Cups of tea at the same temperature
of oxygen (O), silicon (Si), aluminum (Al), and iron (Fe) have equal thermal energy. One of Earth’s two main
in a solid state. Some people consider the cryosphere as a sources of energy is the heat energy of its core (called
sub-sphere of the geosphere. The cryosphere is composed geothermal energy ).
of snow crystals and ice that form from freezing parts
of the hydrosphere or atmosphere. Ice is a rock made of ■ Electromagnetic energy is light, an oscillating (wave)
mineral crystals (like snowflakes), so the cryosphere is form of energy perpetuated by coupled electronic
actually a sub-sphere of the geosphere. Most of it exists and magnetic fields emitted from and reflected
in the polar ice sheets (continental glaciers), permafrost by objects. The distance between two crests in the
(permanently frozen moisture in the ground), and sea ice waves of electromagnetic energy is called wavelength .
(ice on the oceans). Humans can only see a small part of the spectrum
of electromagnetic wavelengths that exist in nature.
Hydrosphere Electromagnetic energy from our Sun is called solar
The hydrosphere is all of the liquid water on Earth’s energy and is the other primary source of Earth’s
surface and in the ground (groundwater). Most of the energy (other than geothermal energy).
hydrosphere is salt water in the world ocean, which has ■ Nuclear energy is energy stored in the nuclei
an average depth (thickness) of 3.7 km. However, the (plural of nucleus) of atoms. Inside the Sun,
hydrosphere also includes liquid water in lakes, streams, hydrogen atoms are heated and energized so
and the ground (called groundwater ).
much that collisions among hydrogen atoms
can fuse their nuclei together ( nuclear fusion ).
Atmosphere
This thermonuclear reaction creates one larger
The atmosphere is the gaseous envelope that surrounds helium atom from every four hydrogen atoms,
Earth. It consists of about 78% nitrogen (Ni), 21% oxygen but it also converts some of the nuclear energy
(O), 0.9% argon (Ar) and trace amounts of other gases like into electromagnetic energy (sunlight). Thus, the
carbon dioxide, water vapor, and methane. About 80% of sunlight warming Earth’s surface was transformed
these gases (including nearly all of the water vapor) occur from nuclear energy in atoms of the Sun. In Earth’s
in the lowest layer of the atmosphere (troposphere), which core, nuclei of abundant unstable atoms eventually
has an average thickness of about 16 km (10 miles). From decay (split apart into smaller nuclei, a process called
there, the atmosphere thins and eventually ends (no air) at nuclear fission). This transforms energy from the
about 1000 km above sea level. atomic nuclei into thermal energy. So the two main
sources of energy that power Earth (solar energy,
Biosphere geothermal energy) have actually been transformed
The biosphere is the living part of Earth, the part from nuclear energy.
that is organic and self-replicating. It includes all
bacteria, plants, and animals, so you are a member of ■ Potential energy is energy stored in an object because
the biosphere. of its position in a force field. A force is a push or
a pull, and the most dominant force field affecting
Magnetosphere Earth materials is Earth’s gravity. Think of a small rock
perched on the edge of a cliff. The rock has energy
Earth’s magnetosphere is its magnetic force field; not a stored within it as a result of the fact that it is being
material. It is generated from the core of the planet, and it pulled by Earth’s gravitational force field. Gravity
is important because it shields Earth from the solar wind will cause the rock to fall if it happens to drop off the
(a radiation of energy and particles from the Sun) that edge of the cliff (whereupon the potential energy is
would otherwise make our planet lifeless.
converted to kinetic energy).
Sometimes, objects change shape (i.e., they experience
Energy Sources and Sinks elastic strain) as potential energy builds up within them,
Energy is the capacity to be active or do work, so matter and their potential energy can also be called elastic energy
does not move unless it has energy. (instead of just potential energy). For example, if you bend
Earth’s spheres would never change without their energy. a ruler, the ruler has energy stored within it because of the

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