Lesson 8: The Earth's Internal Heat Flashcards
a very thin layer when compared to the 3 other layers of the Earth
crust
the largest layer of the earth being a estimated 1800 miles thick
mantle
very hot dense rock
magma
the mantle is kept in a
semi-liquefied state
composed of very hot dense rock called magma, because of the high
temperatures with the Mantle, the rock is kept in a semi-liquefied state.
mantle
composed of liquefied metals such as nickel ad iron. It is kept in it liquefied
state because of the immense heat with this layer
outer core
also composed
of metals however they are not kept in a liquefied state. It is believed that the
temperature and pressure at depth is so great that the metals are squeezed tightly
together restricting movement, so much that the particles have to vibrated in place
almost like a soild structure.
inner core
sources of heat in our planet
primordial and radiogenic heat
the internal heat energy that gradually
gathered together by means of dispersion in the planet during its few million years
of evolution
primordial heat
The major contribution of this internal heat
is the
accretional energy
the energy deposited during the early formation of a planet
accretional energy
a storage of primordial heat that originates from times of accretion when
kinetic energy of colliding particles was transformed into thermal energy.
the core
the heat of the core takes ______ years to reach the surface of the Earth
tens of thousands of years
the thermal energy released as a result of spontaneous
nuclear disintegration
radiogenic heat
natural radioactive elements inside the Earth that disintegrate; involved in radiogenic heat
uranium, thorium, and potassium
a special kind of element because when it decays, heat
(radiogenic) is produced.
uranium
approximate terawatts in the flow of heat in the Earth’s interior to its surface
47 terawatts
Without the process of radioactive decay, there would be
fewer volcanoes and earthquakes and less formation of mountain ranges
produced by the radioactive decay of isotopes in
the mantle and crust
radiogenic heat
left over from the formation of
the Earth.
primordial heat
three processes that can transfer heat
conduction, convection, and radiation
governs the thermal conditions in almost entire solid portions of the
Earth and plays a very important role in the lithosphere. Its processes happen in the
earth’s surface.
conduction
e defined as the process by which heat energy
is transmitted through collisions between neighboring atoms or molecules. Heat from
the Earth’s core and radiation from the Sun is transferred to the surface of
the Earth by this
conduction
involves transfer of heat by the movement of mass, which is a more
efficient means of heat transport in the Earth compared to pure conduction; dominates the thermal conditions in the zones where large quantities of
fluids (molten rocks) exist, and thus governs the heat transport in the fluid outer
core and the mantle
convection
causes the mantle to move slowly from the interior up to the surface, resulting in the movement of tectonic plates
convection current
how are volcanoes formed in terms of convection?
hot materials are added at the edges of a plate and cools. these edges become dense by its exposure from the heat and sinks into the Earth at ocean trenches
the least important mode of heat transport in the Earth. The process of
heat exchange between the Sun and the Earth controls the
temperatures at the Earth’s surface.
Radiation
Inside the Earth, radiation is significant only in
the hottest parts of the
core and lower mantle
When the land and water become
warm in summer, they emit
long-wavelength infrared radiation
