Lecture 3 Ch 1 Review Temperature & Heat Transfer

1. Lecture 3Ch 1 Review Temperature &Heat Transfer

2. Review: Thermal Structure • Thermosphere – very high temperatures, the sun warms N2 and O2 and heats up the rarefied “air”. Temperature is high due to the interactions of the energized molecules bumping into one another. No well defined top. • Mesosphere– returns to normal temperature decrease with height, top is called the Mesopause • Stratosphere – sun warms ozone, ozone warms the air, temperature increases with height, top is called the Stratopause • Troposphere – warmed by earth decreases with height, top is called Tropopause ~85 km and above, -90 to > 40 C° ~50 km to ~85 km, ~0 to -90 C° ~12 km to ~50 km -60 to ~0 C° Surface to 12 km, ~20 to -60 C°

3. Ionosphere • Located between 80-400 km • Overlaps with the Thermosphere • Is an electrically charged layer • No influence on daily weather • The ionosphere is also the site of Aurora – Pretty!! • Important for long wave radio transmission • Travel straight lines and bounce off the Ionosphere • Go farther at night, F layer reflects AM waves • In daylight, D layer absorbs AM waves

4. Auroras • Aurora borealis (northern lights) • Aurora australis (southern lights) • Closely correlated with solar-flares • Geographic location is important • (Earth’s magnetic poles) • Appear in the night sky as overlapping curtains • Bottom at 100 km (62 miles) • Tops at 400 km (248 miles or higher)

5. Aurora Borealis from the International Space Station

6. Aurora Borealis from the surface (Norway)

7. Reminder from First Class • Weather • The state of the atmosphere at any given time. • Climate • A description of aggregate weather conditions. • The sum of all statistical weather information that helps describe a place or region. “Climate is what you expect, but weather is what you get”

8. Weather • Weather is the condition of the atmosphere at any particular time • Air Temperature • Air Pressure • Humidity • Clouds • Precipitation • Visibility • Wind

9. Climate • Average range of “weather elements” over a long period of time. • How hot, cold, wet, dry…. • Includes the “extreme” weather event too. • Droughts, heat wave, cold snaps…. • Climate changes on geological time scales • think ice ages and non ice ages

10. Kinetic Energyand Temperature • The energy within a body that is a result of its motion! • Temperature(i.e. of air) is a measure of its average kinetic energy. • describes how warm or cold an object is.

11. Heat • The TRANSFER of energy into or out of an object because of TEMPERATURE DIFFERENCES • It is theFLOWof energy! • After heat is transferred it is stored as internal energy.

12. Temperature Scales Fahrenheit Celsius Kelvin

13. Fahrenheit Based on “Fixed Points” – coldest temperature he could measure and assumed human body temp. Freezing is at 32 and Boiling is a 212. 180 Divisions between Freezing and Boiling We use this temperature scale here in the USA.

14. Celsius Decimal Scale powers of 10 0 degrees = Freezing 100 degrees = Boiling 100 between Freezing and Boiling Scientists use this.

15. Kelvin Called the “Absolute Scale” Same Spacing as Celsius 100 divisions between boiling and freezing 0 K = the temperature at which all molecular motion is presumed to cease Absolute Zero= molecules stop moving, no thermal motion.

16. Latent Heat • The heat energy required to change a substance from one state to another. • Example: • Water from solid to liquid • temperature stays constant. • Heat is used to MELT the ice does not produce a temperature change

17. ENERGY and PHASE CHANGES Sublimation Melting Evaporation SOLID LIQUID GAS • Heat is ABSORBED from the environment • Solid Liquid: Melting • Liquid  Gas: Evaporation (COOLING Process) • Solid  Gas: Sublimation

18. ENERGY and PHASE CHANGES • Heat is RELEASED into the environment • Gas Liquid: Condensation • Liquid  Solid: Freezing (WARMING Process) • Gas  Solid: Deposition SOLID LIQUID GAS Freezing Condensation Deposition

19. PHASE CHANGES Sublimation Melting Evaporation SOLID LIQUID GAS Freezing Condensation Deposition

20. Mechanisms of Heat Transfer

21. Conduction • The TRANSFER of heat through election and molecular collisions from one molecule to another. • Ability to conduct varies: • Metals are better • Air doesn’t conduct well, called an INSULATOR Only important for heating the air in DIRECT contact with the surface of the Earth

22. Convection • Heat transfer that involves the actual movement or circulation of substance • Air and water • Most common form of transfer in the atmosphere • Thermals • Advection = horizontal movement.

23. Radiation • Travels through the vacuum of space! • How solar energy reaches the planet!

24. RADIATION CONDUCTION CONVECTION RADIATION

25. Solar Radiation • Electromagnetic Radiation! • Wavelengths – the distance from one crest to the next • All types travel at 300,000 km/sec or 186,000 miles/sec

26. Earth emits radiation at longer wavelengths than the sun. Emits considerably less radiant energy than the sun Over 95% of the Earth’s radiation has wavelengths between 2.5 and 30 micrometers (Infrared) Radiation emitted by the Earth

27. Laws of Radiation - 1 • ALL objects continually emit radiant energy over a range of wavelengths • Sun emits energy • Earth emits energy • YOU emit energy • EVERYTHING emits energy... • Unless it’s at “absolute zero” when molecules stop moving

28. Laws of Radiation - 2 • Hotter objects radiate more energy in the form of short wavelength radiation than cooler objects • Hot burner on a stove glows Red • Cool burner on a stove doesn’t glow at all but could still FEEL hot

29. Laws of Radiation - 3 • Hotter objects radiate more total energy per unit area than do cooler objects • Sun is 6000 K (10,000 F) • Earth is 289 K (59 F) • Sun 160,000 times more energy than the Earth • This concept is called the Stephan-Boltzman Law Don’t worry, you don’t need to memorize this!

30. HOMEWORK DUE THURSDAY Hand in your homework to me. Name on all pieces of paper and stapled.