Transcript Heat transfer PPT

Review of Layers of the
Atmosphere
 http://studyjams.scholastic.com/studyjams/ja
ms/science/weather-and-climate/earthsatmosphere.htm
Heat Transfer
 Heat transfer is the movement of
thermal energy from a warmer item
to a cooler item.
 Remember, heat moves in
predictable ways, from a high to a
low.
If I open the front door, does the
heat go OUT or does the cold
come IN?
The thermal
energy goes
from HOT
areas to
COLD. The
heat goes
OUT
Heating of the Earth
 The Sun provides most of Earth’s energy.
 The Sun’s energy can be
– Reflected back into space by clouds, particles,
or Earth’s surface
– Absorbed by the atmosphere
– Absorbed by the surface- land and water
 This heat energy causes wind and ocean
currents.
Three types of heat transfer
Conduction
Convection
Radiation
Conduction
 Conduction is heat transfer through
solids.
 The transfer of heat between
substances that are in direct contact.
Examples:
 Your feet transfer
(conduct) heat to a cold
tile floor
 A spoon placed in hot
soup becomes warmer as
the spoon conducts heat
away from the hot soup
Conduction examples
 Conductors are
materials that allow
heat to pass through
easily.
 Ex. Metals are the
best conductors of
heat, whereas air is
the worst conductor of
heat.
 Which one(s) are
good conductors?
 Insulators are
materials that
do not allow
heat to pass
through easily
 Examples:
glass, ceramics
and rubber
 Which spoon is a conductor? Which spoon
is an insulator?
 Which spoon would you choose to stir with
and why?
–Convection: transfer of heat
from one place to another
through circulation of material.
Example, heat flowing through
air or water
In the ocean, warm currents move heat
from the equator to higher latitudes
through convection currents.
More direct
light at the
equator =
warmer
ocean
temperatures
at the
equator
 Convection occurs in fluids
 A fluid is defined as a liquid or gas
because fluids have the ability to flow
from one place to another
 Solids, however, maintain their
position
Convection within the Earth
Divergent
Boundary
Mid Ocean Ridge
Material
in the
mantle is
heated by
the outer
core and
it rises,
pushing
apart the
plates of
the crust
Convergent
Boundary
Trench
 How do you feel the Sun’s heat
even when you aren’t in direct
contact with it?
Radiation: transfer of heat from
one place to another in the form
of rays or waves.
Examples heat from the sun,
microwave
 Heat can travel in waves without a
medium (a liquid, solid, or gas).
 Radiation is the term that describes
heat movement without a medium of
matter.
Review
 Conduction
 Convection
 Radiation
Convection
Conduction
Conduction
Radiation
Convection
Radiation
Conduction
 Can you explain why you feel warm when
you are standing away from a campfire?
– Radiation
 Why does a carpeted floor feel warmer to
bare feet than tile even though both surfaces
are the same temperature?
– Better conductor
 What information would you need in order to
predict whether heat transfer would occur
when two objects or materials interact?
– Are they the same temperature? If no, then heat
will flow from the hotter object to the colder one.
– Is it an insulating material or a conducting
material? If it is insulating, there will be little or no
heat transfer.
Name each type of heat transfer
Review Videos
 http://www.wisconline.com/objects/heattransfer/
 (with audio)
 http://vitalnj.pbslearningmedia.org/asset/lsps
07_int_heattransfer/
 PBS heat transfer tutorial
http://www.youtube.com/watch?v=wr8Z4SCE
TPs
Heat transfer song, by Mr. Parr