Transcript Heat Transfer in the Atmosphere PowerPoint

HEAT TRANSFER IN THE
ATMOSPHERE
REVIEW
•
TEMPERATURE
•
HEAT TRANSFER TYPES
• THE AVERAGE AMOUNT OF ENERGY OF MOTION OF EACH PARTICLE IN A
SUBSTANCE.
–
CONDUCTION
–
CONVECTION = HEAT TRANSFER BY THE MOVEMENT OF MOLECULES IN A FLUID
–
RADIATION = HEAT TRANSFER WITHOUT THE OBJECTS COMING IN CONTACT WITH EACH
OTHER
= HEAT TRANSFER BY OBJECTS IN DIRECT CONTACT WITH EACH OTHER
WHAT HAPPENS TO DENSITY WHEN
TEMPERATURE INCREASES?
WHEN THE SAME NUMBER OF MOLECULES (SAME MASS) TAKE UP MORE SPACE
(MORE VOLUME), THE DENSITY DECREASES.
WHEN THE MOLECULES BOUNCE IN OPPOSITE DIRECTIONS, THEY SPREAD OUT AND
TAKE UP MORE SPACE (MORE VOLUME)
WHEN THE MOLECULES COLLIDE THEY BOUNCE IN OPPOSITE
DIRECTIONS
WHEN THE MOLECULES MOVE FASTER THEY COLLIDE WITH EACH OTHER
MORE
WHEN TEMPERATURE INCREASES, THE MOLECULES MOVE FASTER (BY
DEFINITION OF TEMPERATURE)
WHAT HAPPENS TO DENSITY WHEN
TEMPERATURE DECREASES?
WHEN TEMPERATURE DECREASES, THE MOLECULES MOVE SLOWER (BY
WHEN THE MOLECULES MOVE SLOWER THEY COLLIDE WITH
THEY COLLIDE WITH EACH OTHER LESS
WHEN THE MOLECULES DON’T COLLIDE AS MUCH, THEY TEND TO STAY
THEY TEND TO STAY CLOSER TOGETHER (LESS VOLUME)
WHEN THE SAME NUMBER OF MOLECULES (SAME MASS) TAKE UP LESS
CHANGES IN PHASES OF MATTER
TEMPERATURE AND ENERGY INCREASING
SOLID
LIQUID
GAS
TEMPERATURE AND ENERGY DECREASING
Phase Changes
In order to change from:
Solid to Liquid
Liquid to Gas
Gas to Liquid
Liquid to Solid
A substance must:
Increase heat
energy
Increase heat
energy
Decrease heat
energy
Decrease heat
energy
The molecules move:
Faster and
farther apart
Faster and
farther apart
Slower and closer
together
Slower and closer
together
HEAT TRANSFER AT THE MOLECULAR
LEVEL
• MOLECULES WITHIN A SUBSTANCE
TRANSFER THEIR HEAT ENERGY WHEN
THEY COLLIDE WITH EACH OTHER
• THE CLOSER MOLECULES ARE (more
dense), THE FASTER HEAT ENERGY WILL
BE TRANSFERRED
• ASSUMING THAT THE DIFFERENT
PHASES ARE MADE OF THE SAME
SUBSTANCE, SOLIDS TRANSFER HEAT
FASTEST, FOLLOWED BY LIQUIDS, AND
GASES ARE THE SLOWEST
TEMPERATURE VS. DENSITY
CONTINUED
• EVEN WITHIN THE SAME STATE OF MATTER,
WARMER SUBSTANCES EXPAND AND BECOME
LESS DENSE THAN COOLER SUBSTANCES
THE EIFFEL TOWER IS 8
INCHES TALLER IN THE
SUMMER THAN IN THE
WINTER
HOT WATER AT THE
BOTTOM OF A POT OF
BOILING WATER RISES
WHILE COOL WATER
FROM THE TOP SINKS
(CREATES CONVECTION
CURRENTS)
WARM AIR RISES AND
COOL AIR SINKS
(CREATES CONVECTION
CURRENTS)
CONVECTION CURRENTS
UNDERGROUND
MAGMA LOSES HEAT ENERGY TO THE
CRUST AS IT PUSHES THE SURFACE PLATES
AS MAGMA
AS THE MAGMA
COOLS, IT
EXPANDS FROM
THE ADDITIONAL
HEAT, IT
CONTRACTS AND
BECOMES MORE
BECOMES LESS
DENSE AND
RISES TO THE
SURFACE
DENSE SO IT
SINKS BACK
TOWARD THE
CORE
MAGMA IS HEATED BY THE
EARTH’S CORE
CONVECTION CURRENTS IN THE AIR
THE WARM AIR COOLS AS IT RISES
(TEMPERATURES IN THE TROPOSPHERE
FALL AS ALTITUDE INCREASES)
AS THE AIR IS
WARMED BY
HEAT RADIATING
BACK FROM THE
EARTH, IT
EXPANDS AND
RISES
AS THE AIR
COOLS, IT
CONTRACTS
AND FALLS BACK
TOWARD
EARTH’S
SURFACE
THE COOLER AIR RUSHES TO FILL THE VOID LEFT
BY THE RISING WARM AIR (CREATING WIND)
TEMPERATURE VS. ALTITUDE
• AS ALTITUDE INCREASES:
• TEMPERATURE IN THE
TROPOSPHERE
DECREASES
• TEMPERATURE IN THE
STRATOSPHERE
INCREASES
• TEMPERATURE IN THE
MESOSPHERE
DECREASES
• TEMPERATURE IN THE
THERMOSPHERE
INCREASES
WHY DOES TEMPERATURE FALL AS
YOU GO UP IN THE TROPOSPHERE?
•
EARTH’S SURFACE IS HEATED BY RADIATION FROM THE SUN (SOLIDS AND
LIQUIDS HEAT MORE QUICKLY THAN GASES)
•
AIR IN THE LOWER TROPOSPHERE IS WARMED BY HEAT RADIATING BACK OFF OF
EARTH’S SURFACE
•
RADIATED HEAT IS TRAPPED BY “GREENHOUSE GASES” (MOSTLY CO2 AND
METHANE)
•
GREENHOUSE GASES ARE FOUND IN
THEIR HIGHEST CONCENTRATIONS
CLOSE TO THE EARTH’S SURFACE
•
THERE IS NOT ENOUGH RADIATED
HEAT ENERGY LEFT TO HEAT THE
AIR IN THE UPPER TROPOSPHERE
WHY DOES TEMPERATURE RISE AS
YOU GO UP IN THE STRATOSPHERE?
• UPPER LAYER OF STRATOSPHERE HAS HIGH CONCENTRATION
OF OZONE (OZONE LAYER)
• OZONE ABSORBS ENERGY FROM UV RADIATION FROM THE SUN
•
EXTRA ENERGY CAUSES
MOLECULES TO MOVE
FASTER AND COLLIDE MORE,
WHICH LEADS TO HIGHER
TEMPERATURES
WHY DOES TEMPERATURE FALL AS
YOU GO UP IN THE MESOSPHERE?
• THE MOLECULES IN THE MESOSPHERE ARE SPREAD VERY FAR APART (LOW
DENSITY)
– DESPITE ITS LOW DENSITY, IT IS STILL MORE DENSE THAN THE NEXT
LAYER ABOVE IT (THE THERMOSPHERE) WHICH IS WHY METEOROIDS BURN
UP FROM THE FRICTION HERE
• AS A RESULT, THE
MOLECULES DO NOT
COLLIDE OFTEN
• FEWER COLLISIONS OF
MOLECULES RELEASES
LESS HEAT, SO
TEMPERATURES ARE LOWER
WHY DOES TEMPERATURE RISE AS
YOU GO UP IN THE THERMOSPHERE?
•
THE THERMOSPHERE IS THE OUTERMOST LAYER OF EARTH’S
ATMOSPHERE SO IT IS SUBJECTED TO MORE DIRECT SOLAR
RADIATION THAN ANY OTHER LAYER
•
THIS EXTREME RADIATION LEADS TO THE IONIZATION (LOSING AND
GAINING ELECTRONS) OF MANY AIR MOLECULES
– THESE IONS ARE RESPONSIBLE FOR THE AURORA BOREALIS
(NORTHERN LIGHTS)
•
IONS TEND TO ABSORB AND
CONDUCT ENERGY (INCLUDING
HEAT ENERGY) VERY WELL SO THE
TEMPERATURE RISES
• BECAUSE THE DENSITY OF
THIS LAYER IS SO LOW, YOU
COULD ACTUALLY FREEZE TO
DEATH DESPITE THE 1000oC
TEMPERATURES (NOT ENOUGH
MOLECULES TO TRANSFER
HEAT TO YOUR SKIN)