Heat Transfer
Chapter 16 Section 2
Pages 532-535
Energy
•
Nearly all energy in Earth’s atmosphere
comes from the sun.
•
Gases are made of molecules that are
constantly moving. The faster they are
moving the more energy they have.
Thermal Energy
•
Is the total energy of motion in the
molecules of a substance.
Temperature
•
The average amount of energy of motion
in the molecules of a substance.
•
It is a measure of how hot or cold
something is.
Measuring Temperature
•
Thermometer- An instrument used to
measure the temperature, consisting of a
thin, glass tube with a bulb on one end
that contains a liquid, usually mercury or
alcohol.
– Liquids expand when heated or
contract when cooled.
– It is measured in degrees Celsius or
Fahrenheit.
•
•
Freezing 0°C = 32°F
Boiling 100°C = 212°F
Heat
•
The energy transferred from a hotter
object to a cooler one.
•
Three ways it is transferred.
– Radiation
– Conduction
– Convection
Radiation
•
The direct transfer of energy by
electromagnetic waves.
–
The heat felt from a campfire or the sun’s rays.
(travels in the form of Infrared radiation)
Radiation
Conduction
•
•
•
The transfer of heat from one substance
to another by direct contact of particles of
matter.
Fast moving molecules bump slower
moving molecules and transfers some of
it’s energy.
The closer the molecules, the more
effectively they conduct heat.
Convection
• The transfer of heat by movements of a
fluid. (liquids or gases)
• Molecules move from place to place
carrying their energy (heat) along with
them.
Convection
Heat Transfer in the Troposphere
• Radiation, conduction and convection
work together to heat the troposphere.
• The surface absorbs solar energy.
• Air near the surface is warmed by
radiation and conduction of heat from the
surface to the air.
Heat Transfer in the Troposphere
• Convection causes most of the heating of
the troposphere.
• Convection Current– Heated molecules have more energy.
– They move faster and spread further apart.
– Air becomes less dense and rises.
– Cooler air is more dense and sinks.
– Moves into the place of the rising air.
Heat Transfer in the Troposphere