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MeteorologyMeteorology
Chapter 17Chapter 17
The Atmosphere: Structure The Atmosphere: Structure and Temperatureand Temperature
Discovery Video Field TripDiscovery Video Field Trip
1.1. What protects Earth from the hot What protects Earth from the hot and cold extremes of space?and cold extremes of space?
2.2. How do clouds form?How do clouds form?
Watch movie then answer questions Watch movie then answer questions aboveabove
17.1 Atmosphere 17.1 Atmosphere CharacteristicsCharacteristics
• Weather – the state of Weather – the state of the atmosphere at a the atmosphere at a given time and place given time and place
• Weather is constantly Weather is constantly changing.changing.
• Climate - based on Climate - based on observations of weather observations of weather that have been collected that have been collected over many years. over many years. – helps describe a placehelps describe a place
17.1 Composition of the 17.1 Composition of the AtmosphereAtmosphere
• Air is a mixture of different gases and Air is a mixture of different gases and particlesparticles
• Nitrogen and Oxygen make up 99% of airNitrogen and Oxygen make up 99% of air• Argon .93% of the airArgon .93% of the air• Carbon Dioxide .039% of the airCarbon Dioxide .039% of the air• All others .031% of the airAll others .031% of the air
Do composition of the Atmosphere Do composition of the Atmosphere worksheetworksheet
17.1 Atmosphere Characteristics17.1 Atmosphere Characteristics• Water vapor is the source of all clouds and Water vapor is the source of all clouds and
precipitation. precipitation. • Carbon Dioxide and water vapor absorbs Carbon Dioxide and water vapor absorbs
heat given off by Earth and solar energy.heat given off by Earth and solar energy.• Large particles like dust sometimes cloud Large particles like dust sometimes cloud
the sky, but these particles are too heavy the sky, but these particles are too heavy to remain suspended for a long time. to remain suspended for a long time.
• Small particles remain suspended for Small particles remain suspended for longer periods of times.longer periods of times.– Sea Salts from breaking waves, fine soil blown Sea Salts from breaking waves, fine soil blown
into air, smoke and soot from fires, pollen and into air, smoke and soot from fires, pollen and microorganisms lifted by the wind, ash and microorganisms lifted by the wind, ash and dust from volcanic eruptionsdust from volcanic eruptions
17.7 Atmosphere Characteristics17.7 Atmosphere Characteristics
• Ozone – form of oxygen that Ozone – form of oxygen that combines three atoms into each combines three atoms into each moleculemolecule– Concentrated in a layer between 10 and Concentrated in a layer between 10 and
50 km above Earth50 km above Earth– absorbs potentially harmful UV radiation absorbs potentially harmful UV radiation
from the sunfrom the sun
17.7 Atmosphere Characteristic 17.7 Atmosphere Characteristic •Primary pollutants are Primary pollutants are
emitted directly from emitted directly from identifiable sourcesidentifiable sources
•Secondary pollutants Secondary pollutants are not emitted are not emitted directly into the airdirectly into the air
•Photochemical Photochemical reaction are reactions reaction are reactions that are triggered by that are triggered by strong sunlightstrong sunlight
• The atmosphere thins as you travel away from The atmosphere thins as you travel away from EarthEarth
• Atmospheric Pressure- the weight of the air Atmospheric Pressure- the weight of the air aboveabove– Sea level – little more than 1kg per square cmSea level – little more than 1kg per square cm
17.117.1• The atmosphere can be divided into four layersThe atmosphere can be divided into four layers
– TroposphereTroposphere• Bottom layer Bottom layer
• Temperature decreases with increase in altitudeTemperature decreases with increase in altitude
– StratosphereStratosphere• Temperature remains constant till 20 km - Then gradually Temperature remains constant till 20 km - Then gradually
increasesincreases
• Contains ozoneContains ozone
– MesosphereMesosphere• Temperature approach -90 degrees CTemperature approach -90 degrees C
– ThermosphereThermosphere• Contains only a tiny fraction of the atmosphere’s massContains only a tiny fraction of the atmosphere’s mass
• Temperatures increase because oxygen and nitrogen absorb Temperatures increase because oxygen and nitrogen absorb short-wave, high energy radiationshort-wave, high energy radiation
17.1 Earth-Sun 17.1 Earth-Sun RelationshipsRelationships
• Nearly all energy that drives Earth’s Nearly all energy that drives Earth’s weather and climate comes from the sunweather and climate comes from the sun
• Seasonal changes occur because Earth’s Seasonal changes occur because Earth’s position relative to the sun continually position relative to the sun continually changes as it travels along its orbit.changes as it travels along its orbit.
• Earth’s motionsEarth’s motions– Rotation: Earth spinning on its axis, 24 hoursRotation: Earth spinning on its axis, 24 hours– Revolutions: Earth orbit around the sunRevolutions: Earth orbit around the sun
17.1 Solstices and 17.1 Solstices and EquinoxesEquinoxes• Summer Solstice- first day of Summer Solstice- first day of
summer (June 21)summer (June 21)
• Winter Solstice- first day of winter Winter Solstice- first day of winter (December 21)(December 21)
• Autummal Equinox- first day of fall Autummal Equinox- first day of fall (September 22)(September 22)
• Spring Equinox- first day spring Spring Equinox- first day spring (March 21)(March 21)
17.2 Heating the 17.2 Heating the AtmosphereAtmosphere• Heat- the energy Heat- the energy
transferred from one transferred from one object to another object to another because of a because of a difference in their difference in their temperaturestemperatures
• Temperature- Temperature- measure of the measure of the average kinetic average kinetic energy of the energy of the individual atoms or individual atoms or molecules in a molecules in a substancesubstance
17.2 Energy Transfer as 17.2 Energy Transfer as HeatHeat• Three mechanism of energy transfer:Three mechanism of energy transfer:
1.1. conductionconduction
2.2. convectionconvection
3.3. radiationradiation
17.2 Conduction17.2 Conduction• Conduction- transfer of Conduction- transfer of
heat through heat through mattermatter by by molecular activitymolecular activity
• Heat flows from higher Heat flows from higher temps to lowertemps to lower
• Metals = good Metals = good conductorsconductors
• Air = poor conductorsAir = poor conductors
• As a whole, conduction As a whole, conduction is the least important is the least important mechanism of heat mechanism of heat transfertransfer
17.2 Convection17.2 Convection• Convection- transfer of Convection- transfer of
heat by mass heat by mass movement or movement or circulation within a circulation within a substance.substance.
• Heating waterHeating water
17.2 Radiation17.2 Radiation• Radiation- the transfer of energy, heat, through Radiation- the transfer of energy, heat, through
space by electromagnetic space by electromagnetic waveswaves
17.2 Four laws governing 17.2 Four laws governing radiationradiation1.1. All objects, at any temperature, All objects, at any temperature,
emit radiant energy emit radiant energy 2.2. Hotter objects radiate more total Hotter objects radiate more total
energy per unit area energy per unit area 3.3. The hotter radiating bodies produce The hotter radiating bodies produce
the shortest wavelengths of the shortest wavelengths of maximum radiationmaximum radiation
4.4. Objects that are good absorbers of Objects that are good absorbers of radiation are good emitter as wellradiation are good emitter as well
17.2 What Happens to Solar 17.2 What Happens to Solar Radiation?Radiation?
1.1. Some energy is absorbed by the object.Some energy is absorbed by the object.-then converted to heat and causes increase -then converted to heat and causes increase
in tempin temp
2.2. water and air are transparent to certain water and air are transparent to certain wavelengths of radiationwavelengths of radiation
3.3. Some radiation may bounce off the Some radiation may bounce off the object without being absorbed or object without being absorbed or transmittedtransmitted
17.2 Reflection and 17.2 Reflection and ScatteringScattering• Reflection- when light bounces off an Reflection- when light bounces off an objectobject
• Scattering- produces a larger number of Scattering- produces a larger number of weaker rays that travel in different weaker rays that travel in different directionsdirections
• About 30% of the solar energy that About 30% of the solar energy that reaches the outer atmosphere is reflectedreaches the outer atmosphere is reflected
• Scattering accounts from the brightness Scattering accounts from the brightness and blue skyand blue sky
17.2 Absorption17.2 Absorption• 50% of the solar energy is absorbed by land 50% of the solar energy is absorbed by land
and seaand sea
• Greenhouse effect- the heating of Earth’s Greenhouse effect- the heating of Earth’s surface and atmosphere from solar radiation surface and atmosphere from solar radiation being absorbed and emitted by the atmosphere being absorbed and emitted by the atmosphere mainly by water vapor and carbon dioxidemainly by water vapor and carbon dioxide
http://www.youtube.com/watch?v=5zLuqSYF68E
http://www.youtube.com/watch?v=7wTVJpjOJAA
17.3 Temperature Controls17.3 Temperature Controls• Factors affecting temp:Factors affecting temp:
– latitude latitude – heating of land and waterheating of land and water– AltitudeAltitude– geographic positiongeographic position– cloud cover cloud cover – ocean currentsocean currents
• Land heats more rapidly and to higher Land heats more rapidly and to higher temperatures than water.temperatures than water.
• Land also cools more rapidly and to lower Land also cools more rapidly and to lower temperatures than water.temperatures than water.
17.3 Geographic Position17.3 Geographic Position• Albedo- fraction of total radiation that is Albedo- fraction of total radiation that is
reflected by any surface.reflected by any surface.
• Many clouds have a high albedoMany clouds have a high albedo
• At night clouds have the opposite effect. Absorb At night clouds have the opposite effect. Absorb outgoing radiation from the earth and outgoing radiation from the earth and reradiating a portion of it back to the surface.reradiating a portion of it back to the surface.
17.3 Isothermal map17.3 Isothermal map• Isotherms- lines that connect points that have Isotherms- lines that connect points that have
the same temperatures. the same temperatures.
Chapter 18 – Section 1Chapter 18 – Section 1
• Precipitation – water vapor is the source Precipitation – water vapor is the source – Clouds, fog, rain, snow, sleet, hailClouds, fog, rain, snow, sleet, hail
• Water vapor – most important gas in Water vapor – most important gas in atmosphere to understand atmospheric atmosphere to understand atmospheric processesprocesses
Water’s Changes of State Water’s Changes of State 18.118.1• Change state needs transfer of energy (heat)Change state needs transfer of energy (heat)
• Latent Heat - hidden heatLatent Heat - hidden heat– Heat added during actual phase change b/c temp Heat added during actual phase change b/c temp
does NOT change until phase change is completedoes NOT change until phase change is complete
• Endothermic – absorbs heatEndothermic – absorbs heat– Melting – solid to liquidMelting – solid to liquid– Evaporation – Liquid to gasEvaporation – Liquid to gas– Sublimation – Solid to gasSublimation – Solid to gas
• Exothermic – releases heatExothermic – releases heat– Freezing – Liquid to solidFreezing – Liquid to solid– Condensation – Gas to LiquidCondensation – Gas to Liquid– Deposition – Gas to SolidDeposition – Gas to Solid
Humidity 18.1Humidity 18.1• Amount of water in the airAmount of water in the air
• Saturation – when water vapor entering Saturation – when water vapor entering system equals water vapor leaving system equals water vapor leaving systemsystem– Depends on tempDepends on temp
•Warm air = higher saturation levelsWarm air = higher saturation levels
Relative Humidity 18.1Relative Humidity 18.1• Ratio of air’s actual water-vapor content Ratio of air’s actual water-vapor content
compared with the amount it can hold at compared with the amount it can hold at temp and pressuretemp and pressure– Doesn’t show actual quantity of water vaporDoesn’t show actual quantity of water vapor– Indicate how near to saturationIndicate how near to saturation
• Changes byChanges by– Adding more water (increase humidity)Adding more water (increase humidity)– Change tempChange temp
• Increase temp = Increase temp = decrease relative humiditydecrease relative humidity
•Decrease temp =Decrease temp = increase relative humidityincrease relative humidity
Dew Point 18.1Dew Point 18.1• The temp to which a parcel of air would The temp to which a parcel of air would
need to be cooled to reach saturationneed to be cooled to reach saturation– Excess water after cooling condenses into Excess water after cooling condenses into
dew, fog, or a clouddew, fog, or a cloud
• High dew point temp = moist airHigh dew point temp = moist air
• Low dew point temp = dry airLow dew point temp = dry air
