Download Transferring Thermal Energy

Transferring Thermal
Energy
Physical and Geo Content
Before the video…
 Get out a sheet of paper.
 Write an example of each
type of thermal energy
transfer discussed in the
video.
 Bill Nye Clip
After the video
 Draw a diagram of each
type of thermal energy
transfer that you listed
from the video. Include
the heat source, where it
is going, and what it is
heating up.
Thermal Energy
 Thermal Energy: sum of the kinetic and
potential energy of all the molecules in an
object
 Thermal Energy increases as temperature
increases
 Heat is thermal energy that flows from high
temperatures to low temperatures
How is thermal energy transferred?
Three Mechanisms
Conduction
Convection
Radiation
Conduction
 Transfer of thermal energy through
matter by the direct contact of
particles
 Ex:
 Holding snow/ice in your hand
 Holding a cup of coffee
Convection
 Transfer of energy by the motion of
heated particles in a fluid
 Energetic particles move from one spot
to another, carrying energy with them
 Fluid expands as temperature increases
 What does this imply about the
density?
 Convection currents are a rising and
sinking action
Convection
 Examples
 Lava Lamp
 Convection Currents on Earth
Global Circulation Video
 Overall, the Sun heats the surface of the Earth,
and Earth radiates back to space about as much
energy as it receives over the course of a year.
(300)
 Day vs. Night, Poles vs. Tropics  Balancing the
budget! (301)
 Tropics and other places maintain fairly constant
average temps bec heat energy is redistributed
around the world. The continual motion of air and
water reallocates heat energy among Earth’s
surface, oceans, and atmosphere and brings it
into balance.
Energy Transfer in Atmosphere:
 Global Wind Systems (305-6) and refer to video

http://www.mhhe.com/biosci/genbio/tlw3/eBrid
ge/Chp29/animations/ch29/global_wind_circulat
ion.swf
 Wind (282) – air moves in response to density
imbalances created by the unequal heating
and cooling of Earth’s surface, works like air
conditioned building, H  L
 Air Masses (303) – large body of air that takes on
characteristics of the area over which it forms,
cP cT mP mT, air masses move transferring heat
from one area to another to establish heat
balance
Salinity Graph
Thermocline
Energy Transfer in Oceans:
Vertically –
 Water Masses (397-8) – sea ice forms, salt ions are
left, cold salty water becomes denser and sinks, (H
– density current) arctic, salty water migrates
toward the equator along the ocean floor
 Upwelling (405) – upward motion of ocean water,
water originates from the bottom of the ocean and
are cold, surface water is displaced by winds and
replaced by upwelling deep water, waters are rich
in nutrients which support marine life
Energy Transfer in Oceans:
Horizontally –
 Density currents - arctic, salty water migrates toward
the equator along the ocean floor, move slowly in
deep ocean waters (403)
 Surface currents – wind driven and follow wind
patterns, relatively salty midlatitude / subtropical
water carried into polar regions and become colder
and denser and sink (403)
 Gyres – closed, circular current systems, five major
ones, northern hemisphere = clockwise, southern
hemisphere = counterclockwise
--Read page 404 and view the figure
Gyres
Radiation
 Transfer of energy by electromagnetic
waves
 Travel through space regardless of matter
being present or not
 AKA radiant energy
 Ex:
 Standing by a fire to warm your hands
 Sun heating the Earth
Radiation
 In a solid, liquid, or gas radiant energy can
travel through the space between
molecules
 Molecules absorb the radiation, and re-
radiate some of the absorbed energy
 Solids and liquids, molecules are much
closer, causing them to collide more often
 This means gases absorb less radiant
energy, and transmit more, than solids and
liquids
Controlling Heat Flow
 Insulators
 A material that does not allow the flow
of heat
 Wood, plastic, and fiberglass
 Some insulators contain trapped air
pockets which are poor conductors of
heat
 Fleece jackets
 Building insulation