1. ATM OCN 100 Summer 2000 1 ATM OCN 100 - Summer 2000 LECTURE 5 AIR TEMPERATURE: A Fundamental Weather Element u A. BACKGROUND u B. THERMOMETRY u C. CLIMATOLOGY of NEAR-SURFACE AIR TEMPERATURE

2. ATM OCN 100 Summer 2000 2 C. THE CLIMATOLOGY of NEAR- SURFACE AIR TEMPERATURE (con’t.) u Average Daily Temperatures & Degree-Day Units – Background – Types of Degree-Day Units F Heating Degree-Day Units F Cooling Degree-Day Units F Growing Degree-Day Units – Degree-Day Units Computations (where...)

4. ATM OCN 100 Summer 2000 4 DEGREE-DAY CALCULATIONS u Calculate daily average temperature & then Heating Degree-Day Units:

5. ATM OCN 100 Summer 2000 5 HEATING DEGREE-DAY CALCULATION u If T max = 40 o F and T min = 30 o F, then:

6. ATM OCN 100 Summer 2000 6 DEGREE-DAY CALCULATIONS u Calculate daily average temperature & then Cooling Degree-Day Units:

7. ATM OCN 100 Summer 2000 7 COOLING DEGREE-DAY CALCULATION u If T max = 80 o F and T min = 60 o F, then:

8. ATM OCN 100 Summer 2000 8 D. VARIATION OF OBSERVED AIR TEMPERATURE WITH HEIGHT u Temperature lapse rates – Rate of cooling with height – Units: degrees per meter or feet or kilometers u Layer nomenclature – lapse – inversion – isothermal where... where...

9. ATM OCN 100 Summer 2000 9 LAPSE CONDITIONS LAPSE CONDITIONS Temperature decreases with height

10. ATM OCN 100 Summer 2000 10 INVERSION CONDITIONS INVERSION CONDITIONS Temperature increases with height

11. ATM OCN 100 Summer 2000 11 ISOTHERMAL CONDITIONS ISOTHERMAL CONDITIONS Temperature remains constant with height

12. ATM OCN 100 Summer 2000 12 VERTICAL TEMPERATURE VARIATIONS VERTICAL TEMPERATURE VARIATIONS (con’t) u The Standard Reference Atmosphere u The Temperature Spheres – Troposphere – Stratosphere – Mesosphere – Thermosphere u The boundaries or “pauses”

13. ATM OCN 100 Summer 2000 13 U.S. STANDARD ATMOSPHERE

14. ATM OCN 100 Summer 2000 14 VERTICAL TEMPERATURE VARIATIONS VERTICAL TEMPERATURE VARIATIONS (con’t) u The Standard Reference Atmosphere – The Temperature “Spheres” – The boundaries or “pauses” u Reasons for vertical temperature structure u Implications of vertical temperature structure

15. ATM OCN 100 Summer 2000 15 RADIOSONDE LOCATIONS

16. ATM OCN 100 Summer 2000 16

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18. 18 ATM OCN 100 - Summer 2000 LECTURE 4A ATMOSPHERIC ENERGETICS: HEAT, ENERGY & ENERGY TRANSPORT u A. INTRODUCTION –What maintains the operation of our planetary system?

19. ATM OCN 100 Summer 2000 19 B. ENERGY & POWER u Definitions –Energy: Ability of a system to do work. –Power: Time rate of energy production or consumption. u Importance

20. ATM OCN 100 Summer 2000 20 B. ENERGY & POWER (con’t.) u Types of Energy (In the Atmosphere) –Kinetic –Potential –Radiant –Internal or “heat” energy –Chemical –Physical phase Transformation –Electrical

21. ATM OCN 100 Summer 2000 21 B. ENERGY & POWER (con’t.) u Energy Units –British Thermal Units (BTU) –Calories –Joules u Power Units –Watts

22. ATM OCN 100 Summer 2000 22 C. ENERGY EXCHANGE PROCESSES u Conservation of energy –Energy cannot be created or destroyed; –Energy can change forms; –Energy can be transported; –Specification by Thermodynamics Laws. u Energy transport Requirements –From high energy (hot) to low energy (cold).

23. ATM OCN 100 Summer 2000 23 C. ENERGY EXCHANGE PROCESSES (con’t.) u Types of energy exchange or transport modes –Conduction –Convection –Radiation where...

24. ATM OCN 100 Summer 2000 24 ENERGY TRANSPORT: CONDUCTION u Energy transfer by molecular vibrational motion.  Requires molecular contact: Transport medium is typically a solid. u In general: –Metals are good heat energy conductors; –Air is a poor heat conductor.

25. ATM OCN 100 Summer 2000 25 ENERGY TRANSPORT: CONVECTION u Energy Transport by molecular motion through bulk transport.  Requires movement of medium: Transport medium is a fluid only. u In general: –Fluid density differences drive convection; –Convection works well in air & water.

26. ATM OCN 100 Summer 2000 26 ENERGY TRANSPORT: RADIATION u Energy Transport is by radiating disturbances in electrical & magnetic fields.  Does not requires a medium: Transport most efficient in vacuum. u Radiation is important for maintenance of planetary climate.

27. ATM OCN 100 Summer 2000 27 D. HEAT (or HEAT ENERGY) u Definition –A form of energy; –Proportional to total amount of thermal energy found in object. u Important considerations –Heat Flow F Requires a temperature difference; F Flow from hot to cold. –Sensible heat Vs. Latent heat where...

28. ATM OCN 100 Summer 2000 28 D. HEAT ENERGY (con’t.) u Sensible heat –“Feelable Heat” –Measurement of heat & thermal energy: –Change in heat = constant x temperature change u Latent heat –“Hidden Heat” –Involves Physical Phase Transformation; –No temperature change.

29. ATM OCN 100 Summer 2000 29 E. A PRACTICAL EXAMPLE u WIND-CHILL & WIND-CHILL EQUIVALENT TEMPERATURE –What do these terms mean? –Human significance.

30. ATM OCN 100 Summer 2000 30 BACKGROUND WIND-CHILL & WIND CHILL EQUIV. TEMP. BACKGROUND u HEAT LOSS FROM HUMANS –Radiation; –Convective Heat Loss; –Latent Heat Loss. u CONVECTIVE HEAT LOSS depends upon: –Difference between skin & air temperature; –Wind speed.

31. ATM OCN 100 Summer 2000 31 THE DEFINITIONS u WIND-CHILL –A form of heat energy loss; –Proportional to: F air temperature & F wind speed. –Units: kcal/square meter/hour

32. ATM OCN 100 Summer 2000 32 THE DEFINITIONS (con’t.) u WIND-CHILL EQUIVALENT TEMPERATURE –A temperature-based index; –Air temperature for calm conditions that produces same convective heat loss as actual combination of ambient air temperature & wind speed; –Units degrees Fahrenheit (or Celsius).

33. ATM OCN 100 Summer 2000 33

34. 34 HUMAN COMFORT & SAFETY: Cold Stress u FROST BITE u HYPOTHERMIA