1. Chapter 17 The Atmosphere: Structure and Temperature
Meteorology
Chapter 17
The Atmosphere: Structure and Temperature

2. Discovery Video Field Trip
What protects Earth from the hot and cold extremes of space?
How do clouds form?
Watch movie then answer questions above

3. 17.1 Atmosphere Characteristics
Weather – the state of the atmosphere at a given time and place
Weather is constantly changing.
Climate - based on observations of weather that have been collected over many years.
helps describe a place

4. 17.1 Composition of the Atmosphere
Air is a mixture of different gases and particles
Nitrogen and Oxygen make up 99% of air
Argon .93% of the air
Carbon Dioxide .039% of the air
All others .031% of the air
Do composition of the Atmosphere worksheet

5. 17.1 Atmosphere Characteristics
Water vapor is the source of all clouds and precipitation.
Carbon Dioxide and water vapor absorbs heat given off by Earth and solar energy.
Large particles like dust sometimes cloud the sky, but these particles are too heavy to remain suspended for a long time.
Small particles remain suspended for longer periods of times.
Sea Salts from breaking waves, fine soil blown into air, smoke and soot from fires, pollen and microorganisms lifted by the wind, ash and dust from volcanic eruptions

6. 17.7 Atmosphere Characteristics
Ozone – form of oxygen that combines three atoms into each molecule
Concentrated in a layer between 10 and 50 km above Earth
absorbs potentially harmful UV radiation from the sun

7. 17.7 Atmosphere Characteristic
Primary pollutants are emitted directly from identifiable sources
Secondary pollutants are not emitted directly into the air
Photochemical reaction are reactions that are triggered by strong sunlight

8. The atmosphere thins as you travel away from Earth
Atmospheric Pressure- the weight of the air above
Sea level – little more than 1kg per square cm

9. 17.1 The atmosphere can be divided into four layers Troposphere
Bottom layer
Temperature decreases with increase in altitude
Stratosphere
Temperature remains constant till 20 km - Then gradually increases
Contains ozone
Mesosphere
Temperature approach -90 degrees C
Thermosphere
Contains only a tiny fraction of the atmosphere’s mass
Temperatures increase because oxygen and nitrogen absorb short-wave, high energy radiation

11. 17.1 Earth-Sun Relationships
Nearly all energy that drives Earth’s weather and climate comes from the sun
Seasonal changes occur because Earth’s position relative to the sun continually changes as it travels along its orbit.
Earth’s motions
Rotation: Earth spinning on its axis, 24 hours
Revolutions: Earth orbit around the sun

13. 17.1 Solstices and Equinoxes
Summer Solstice- first day of summer (June 21)
Winter Solstice- first day of winter (December 21)
Autummal Equinox- first day of fall (September 22)
Spring Equinox- first day spring (March 21)

14. http://www.youtube.com/watch?v=rcquRMaVSKU – 10 minutes

15. 17.2 Heating the Atmosphere
Heat- the energy transferred from one object to another because of a difference in their temperatures
Temperature- measure of the average kinetic energy of the individual atoms or molecules in a substance

16. 17.2 Energy Transfer as Heat
Three mechanism of energy transfer:
conduction
convection
radiation

17. 17.2 Conduction
Conduction- transfer of heat through matter by molecular activity
Heat flows from higher temps to lower
Metals = good conductors
Air = poor conductors
As a whole, conduction is the least important mechanism of heat transfer

18. 17.2 Convection
Convection- transfer of heat by mass movement or circulation within a substance.
Heating water

19. 17.2 Radiation
Radiation- the transfer of energy, heat, through space by electromagnetic waves

21. 17.2 Four laws governing radiation
All objects, at any temperature, emit radiant energy
Hotter objects radiate more total energy per unit area
The hotter radiating bodies produce the shortest wavelengths of maximum radiation
Objects that are good absorbers of radiation are good emitter as well

22. 17.2 What Happens to Solar Radiation?
Some energy is absorbed by the object.
-then converted to heat and causes increase in temp
water and air are transparent to certain wavelengths of radiation
Some radiation may bounce off the object without being absorbed or transmitted

24. 17.2 Reflection and Scattering
Reflection- when light bounces off an object
Scattering- produces a larger number of weaker rays that travel in different directions
About 30% of the solar energy that reaches the outer atmosphere is reflected
Scattering accounts from the brightness and blue sky

28. 17.2 Absorption 50% of the solar energy is absorbed by land and sea
Greenhouse effect- the heating of Earth’s surface and atmosphere from solar radiation being absorbed and emitted by the atmosphere mainly by water vapor and carbon dioxide

32. 17.3 Temperature Controls Factors affecting temp:
latitude
heating of land and water
Altitude
geographic position
cloud cover
ocean currents
Land heats more rapidly and to higher temperatures than water.
Land also cools more rapidly and to lower temperatures than water.

33. 17.3 Geographic Position
Albedo- fraction of total radiation that is reflected by any surface.
Many clouds have a high albedo
At night clouds have the opposite effect. Absorb outgoing radiation from the earth and reradiating a portion of it back to the surface.

34. 17.3 Isothermal map
Isotherms- lines that connect points that have the same temperatures.

36. Chapter 18 – Section 1 Precipitation – water vapor is the source
Clouds, fog, rain, snow, sleet, hail
Water vapor – most important gas in atmosphere to understand atmospheric processes

37. Water’s Changes of State 18.1
Change state needs transfer of energy (heat)
Latent Heat - hidden heat
Heat added during actual phase change b/c temp does NOT change until phase change is complete
Endothermic – absorbs heat
Melting – solid to liquid
Evaporation – Liquid to gas
Sublimation – Solid to gas
Exothermic – releases heat
Freezing – Liquid to solid
Condensation – Gas to Liquid
Deposition – Gas to Solid

40. Humidity 18.1 Amount of water in the air
Saturation – when water vapor entering system equals water vapor leaving system
Depends on temp
Warm air = higher saturation levels

41. Relative Humidity 18.1
Ratio of air’s actual water-vapor content compared with the amount it can hold at temp and pressure
Doesn’t show actual quantity of water vapor
Indicate how near to saturation
Changes by
Adding more water (increase humidity)
Change temp
Increase temp = decrease relative humidity
Decrease temp = increase relative humidity

42. Dew Point 18.1
The temp to which a parcel of air would need to be cooled to reach saturation
Excess water after cooling condenses into dew, fog, or a cloud
High dew point temp = moist air
Low dew point temp = dry air