HEAT TRANSFER IN THE ATMOSPHERE

REVIEWREVIEW• TEMPERATURETEMPERATURE

• THE AVERAGE AMOUNT OF THE AVERAGE AMOUNT OF ENERGYENERGY OF MOTION OF EACH PARTICLE IN OF MOTION OF EACH PARTICLE IN A SUBSTANCE.A SUBSTANCE.

• HEAT TRANSFER TYPESHEAT TRANSFER TYPES– CONDUCTIONCONDUCTION = = HEAT TRANSFER BY OBJECTS IN HEAT TRANSFER BY OBJECTS IN DIRECT CONTACT DIRECT CONTACT WITH EACH OTHERWITH EACH OTHER

– CONVECTIONCONVECTION = HEAT TRANSFER BY THE = HEAT TRANSFER BY THE MOVEMENTMOVEMENT OF MOLECULES IN A OF MOLECULES IN A FLUIDFLUID

– RADIATIONRADIATION = HEAT TRANSFER = HEAT TRANSFER WITHOUT WITHOUT THE OBJECTS COMING IN CONTACT WITH THE OBJECTS COMING IN CONTACT WITH EACH OTHEREACH OTHER

WHAT HAPPENS TO WHAT HAPPENS TO DENSITY WHEN DENSITY WHEN

TEMPERATURE INCREASES?TEMPERATURE INCREASES?

WHAT HAPPENS TO WHAT HAPPENS TO DENSITY WHEN DENSITY WHEN

TEMPERATURE DECREASES?TEMPERATURE DECREASES?

CHANGES IN PHASES OF CHANGES IN PHASES OF MATTERMATTER

TEMPERATURE AND ENERGY INCREASING

TEMPERATURE AND ENERGY DECREASING

GAS

LIQUIDSOLID

Phase Changes

In order to change from: A substance must: The molecules move:

Solid to Liquid Increase heat energy

Faster and farther apart

Liquid to Gas Increase heat energy

Faster and farther apart

Gas to Liquid Decrease heat energy

Slower and closer together

Liquid to Solid Decrease heat energy

Slower and closer together

HEAT TRANSFER AT THE HEAT TRANSFER AT THE MOLECULAR LEVELMOLECULAR LEVEL

• MOLECULES WITHIN A SUBSTANCE MOLECULES WITHIN A SUBSTANCE TRANSFER THEIR HEAT ENERGY WHEN TRANSFER THEIR HEAT ENERGY WHEN THEY THEY COLLIDE COLLIDE WITH EACH OTHERWITH EACH OTHER

• THE CLOSER MOLECULES ARE (more THE CLOSER MOLECULES ARE (more dense), THE dense), THE FASTER FASTER HEAT ENERGY HEAT ENERGY WILL BE TRANSFERREDWILL BE TRANSFERRED

• ASSUMING THAT THE DIFFERENT ASSUMING THAT THE DIFFERENT PHASES ARE MADE OF THE SAME PHASES ARE MADE OF THE SAME SUBSTANCE, SUBSTANCE, SOLIDSSOLIDS TRANSFER HEAT TRANSFER HEAT FASTEST, FOLLOWED BY FASTEST, FOLLOWED BY LIQUIDSLIQUIDS, AND , AND GASESGASES ARE THE SLOWEST ARE THE SLOWEST

TEMPERATURE VS. DENSITY TEMPERATURE VS. DENSITY CONTINUEDCONTINUED

• EVEN WITHIN THE SAME STATE OF MATTER, EVEN WITHIN THE SAME STATE OF MATTER, WARMER SUBSTANCES EXPAND AND BECOME WARMER SUBSTANCES EXPAND AND BECOME LESS DENSE THAN COOLER SUBSTANCESLESS DENSE THAN COOLER SUBSTANCES

THE EIFFEL TOWER IS 8 THE EIFFEL TOWER IS 8 INCHES TALLER IN THE INCHES TALLER IN THE SUMMER THAN IN THE SUMMER THAN IN THE

WINTERWINTER

HOT WATER AT THE HOT WATER AT THE BOTTOM OF A POT OF BOTTOM OF A POT OF BOILING WATER RISES BOILING WATER RISES WHILE COOL WATER WHILE COOL WATER FROM THE TOP SINKS FROM THE TOP SINKS

(CREATES CONVECTION (CREATES CONVECTION CURRENTS)CURRENTS)

WARM AIR RISES AND WARM AIR RISES AND COOL AIR SINKS COOL AIR SINKS

(CREATES (CREATES CONVECTION CONVECTION CURRENTS)CURRENTS)

CONVECTION CURRENTS CONVECTION CURRENTS UNDERGROUNDUNDERGROUND

MAGMA IS MAGMA IS HEATEDHEATED BY THE BY THE EARTH’S COREEARTH’S CORE

AS MAGMA AS MAGMA EXPANDSEXPANDS

FROM THE FROM THE ADDITIONAL ADDITIONAL

HEAT, IT HEAT, IT BECOMES BECOMES

LESSLESS DENSE DENSE AND RISES AND RISES

TO THE TO THE SURFACESURFACE

MAGMA LOSES MAGMA LOSES HEAT ENERGY HEAT ENERGY TO THE TO THE CRUST AS IT PUSHES THE SURFACE PLATESCRUST AS IT PUSHES THE SURFACE PLATES

AS THE AS THE MAGMA MAGMA COOLS, IT COOLS, IT CONTRACTS CONTRACTS AND AND BECOMES BECOMES MOREMORE DENSE DENSE SO IT SO IT SINKSSINKS BACK BACK TOWARD THE TOWARD THE CORECORE

CONVECTION CURRENTS IN CONVECTION CURRENTS IN THE AIRTHE AIR

THE COOLER AIR RUSHES TO FILL THE VOID THE COOLER AIR RUSHES TO FILL THE VOID LEFT BY THE RISING WARM AIR (CREATING LEFT BY THE RISING WARM AIR (CREATING

WINDWIND))

THE WARM AIR THE WARM AIR COOLSCOOLS AS IT RISES AS IT RISES (TEMPERATURES IN THE TROPOSPHERE (TEMPERATURES IN THE TROPOSPHERE

FALL AS ALTITUDE INCREASES) FALL AS ALTITUDE INCREASES)

AS THE AIR AS THE AIR COOLS, IT COOLS, IT CONTRACTSCONTRACTS AND FALLS AND FALLS BACK TOWARD BACK TOWARD EARTH’S EARTH’S SURFACESURFACE

AS THE AIR IS AS THE AIR IS WARMED BY WARMED BY

HEATHEAT RADIATING RADIATING BACK FROM THE BACK FROM THE

EARTH, IT EARTH, IT EXPANDS AND EXPANDS AND

RISESRISES

TEMPERATURE VS. TEMPERATURE VS. ALTITUDEALTITUDE

• AS ALTITUDE INCREASES:AS ALTITUDE INCREASES:

• TEMPERATURE IN THE TEMPERATURE IN THE TROPOSPHERE TROPOSPHERE DECREASESDECREASES

• TEMPERATURE IN THE TEMPERATURE IN THE STRATOSPHERE STRATOSPHERE INCREASESINCREASES

• TEMPERATURE IN THE TEMPERATURE IN THE MESOSPHERE MESOSPHERE DECREASESDECREASES

• TEMPERATURE IN THE TEMPERATURE IN THE THERMOSPHERE THERMOSPHERE INCREASESINCREASES

WHY DOES TEMPERATURE WHY DOES TEMPERATURE FALL AS YOU GO UP IN THE FALL AS YOU GO UP IN THE

TROPOSPHERE?TROPOSPHERE?• EARTH’S EARTH’S SURFACE SURFACE IS HEATED BY RADIATION FROM THE SUN (SOLIDS AND IS HEATED BY RADIATION FROM THE SUN (SOLIDS AND

LIQUIDS HEAT MORE QUICKLY THAN GASES)LIQUIDS HEAT MORE QUICKLY THAN GASES)

• AIR IN THE LOWER TROPOSPHERE IS WARMED BY HEAT AIR IN THE LOWER TROPOSPHERE IS WARMED BY HEAT RADIATING RADIATING BACK OFF BACK OFF OF EARTH’S SURFACEOF EARTH’S SURFACE

• RADIATED HEAT IS TRAPPED BY “RADIATED HEAT IS TRAPPED BY “GREENHOUSE GASES” (GREENHOUSE GASES” (MOSTLY MOSTLY COCO22 AND AND METHANE)METHANE)

• GREENHOUSE GASES ARE FOUND IN GREENHOUSE GASES ARE FOUND IN THEIR HIGHEST CONCENTRATIONS THEIR HIGHEST CONCENTRATIONS CLOSE CLOSE TO THE EARTH’S SURFACETO THE EARTH’S SURFACE

• THERE IS NOT ENOUGH RADIATED THERE IS NOT ENOUGH RADIATED HEAT HEAT ENERGYENERGY LEFT TO HEAT THE LEFT TO HEAT THE AIR IN THE UPPER TROPOSPHEREAIR IN THE UPPER TROPOSPHERE

WHY DOES TEMPERATURE WHY DOES TEMPERATURE RISE AS YOU GO UP IN THE RISE AS YOU GO UP IN THE

STRATOSPHERE?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 WHY DOES TEMPERATURE FALL AS YOU GO UP IN THE FALL AS YOU GO UP IN THE

MESOSPHERE?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 WHY DOES TEMPERATURE RISE AS YOU GO UP IN THE RISE AS YOU GO UP IN THE

THERMOSPHERE?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)