1. 1 NATS 101 Lecture 3 TR Weather & Climate Temperature Heat Transfer

2. 2 3” by 5” Cards Name SID Clicker Number Clicker Setup Instructions

3. 3 What is Pressure at 0.8 km? (Tucson, Arizoina) Use Equation for Pressure Change

4. 4 What is Pressure at 1.6 km? (Denver, Colorado) Use Equation for Pressure Change

5. 5 What is Pressure at 8.7 km? (Mt. Everest) Use Equation for Pressure Change

6. Lecture 2-Nats 1016 Weather Weather – The state of the atmosphere: for a specific place at a particular time Weather Elements 1) Temperature 2) Pressure 3) Humidity 4) Wind 5) Visibility 6) Clouds 7) Significant Weather

7. Lecture 2-Nats 1017 Surface Station Model Temperatures Plotted °F in U.S. Sea Level Pressure Leading 10 or 9 is not plotted Examples: 1013.8 plotted as 138 998.7 plotted as 987 1036.0 plotted as 360 Ahrens, p 431 Responsible for boxed parameters

8. Lecture 2-Nats 1018 Sky Cover and Weather Symbols Ahrens, p 431

9. Lecture 2-Nats 1019 Pressure Tendency Change in pressure over the past 3 hours is also plotted. Also called barometric tendency Ahrens, p 432

10. Lecture 2-Nats 10110 Wind Barbs Direction Wind is going towards Westerly Westerly  from the West Speed (accumulated) Each flag is 50 knots Each full barb is 10 knots Each half barb is 5 knots 65 kts from west

11. Wind Speed How to read: Half barb = 5 knots Full barb = 10 knots Flag = 50 knots 1 knot = 1 nautical mile per hour = 1.15 mph = ______ knots

12. Wind direction WESTERLY From the west NORTHERLY From the north EASTERLY From the east SOUTHERLY From the south 270° 360° 90 ° 180°

13. 13 Surface Station Model Temperate ( o F) = 95 o F Pressure (mb) = 1009.8 mb Last three digits Dew Point (later) = 62 o F Moisture Wind Barb= SE @15 kts Direction and Speed Cloud Cover = Overcast Tenths total coverage 95 62 098 Decimal point

14. Lecture 2-Nats 10114 Surface Station Model Temperate ( o F) Pressure (mb) Last Three Digits (tens, ones, tenths) Dew Point (later) Moisture Wind Barb Direction and Speed Cloud Cover Tenths total coverage Ahrens, p 431 72 58 111 Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

15. Lecture 2-Nats 10115 Practice Surface Station Sea Level Pressure Leading 10 or 9 is not plotted Examples: 1013.8 plotted as 138 998.7 plotted as 987 1036.0 plotted as 360 Ahrens, p 431 42 18 998 Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

16. Lecture 2-Nats 10116 temperature dew point SLP pressure wind cloud cover Ohio State website

17. Lecture 2-Nats 10117 Surface Map Symbols Fronts Mark the boundary between different air masses…later Significant weather occurs near fronts Current US Map Ahrens, p 432

18. Lecture 2-Nats 10118

19. So what’s happening above the ground?

20. Lecture 2-Nats 10120 Radiosonde Weather balloons, or radiosondes, sample atmospheric to 10 mb. They measure temperature moisture pressure They are tracked by GPS to get winds

21. Lecture 2-Nats 10121 Radiosonde Distribution Radiosondes released at 0000 and at 1200 GMT for a global network of stations. Large gaps in network over oceans and in less affluent nations. Stations ~400 km apart over North America

22. 22 Upper Air Station Model Temperate ( o C) Height (m or dam) Three digits given Leading and/or last digit(s) missing Dew Point Depression Moisture (later) Wind Barb Direction and Speed -3 11 098 Always missing digit(s)

23. 23 What is Climate? Statistics of weather (averages, ranges, extremes) computed over many years. Year (annual precipitation for Tucson) Season (e.g Winter: Dec-Jan-Feb) Month (e.g January rainfall in Tucson) Date (e.g. Average & record high and lows temperatures for Jan 30 in Tucson)

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26. 26 Climate of Tucson Monthly Averages Individual months can show significant deviations from long-term, monthly means. Average Temperature = (MAX+MIN)/2

27. 27 Average and Record MAX and MIN Temperatures for Date

28. 28 Climate of Tucson Probability of Last Spring Freeze Cool Site: Western Region Climate CenterWestern Region Climate Center

29. 29 Climate of Tucson Probability of Rain Cool Site: Western Region Climate CenterWestern Region Climate Center

30. 30 Climate of Tucson Extreme Rainfall Cool Site: Western Region Climate CenterWestern Region Climate Center

31. 31 Climate of Tucson Snow! Cool Site: Western Region Climate CenterWestern Region Climate Center

32. 32 Summary Weather - atmospheric conditions at specific time and place Weather Maps => Instantaneous Values Climate - average weather and the range of extremes compiled over many years Statistical Quantities => Expected Values

33. 33 Reading Assignment Ahrens Pages 25-30 Problems 2.1-2.4 (2.1 => Chapter 2, Problem 1)

34. 34 Temperature Scales Fahrenheit ( o F) - relative US public standard Celsius ( o C) - relative Freezing point 0 o C Boiling point 100 o C o C= 5/9 ( o F-32) Kelvin (K) - absolute K= o C+273 Ahrens p27

35. 35 What is Temperature? Microscopic View Energy due to random velocity of molecules Related to average molecular speed; 500 m/s at room temperature for air Maxwell Distribution K.E.=(1/2)mv 2 =(3/2)kT m=molecular weight k=Boltzmann constant =1.38065×10 −23 joule/K (joule is unit of energy)

36. 36 Temperature-Density: Charles Law Consider volume of air If air is warmed: The molecules will move faster, have “stronger” collisions, and tend to become spaced farther apart Volume increases, so density decreases Warmer => less dense Charles Law Applet T(K) = constant x Volume at uniform pressure

37. 37 What is Heat? Heat-Energy in the process of being transferred from a warmer object to a cooler object Consider a pot of water on a hot burner. Consider the following questions: Williams, p. 19

38. 38 Heat Transfer Questions What causes the… Pan bottom and handle to get warmer? Top of the water to become warmer? Water temperature to not exceed 100 o C? Region away from side of pan to feel warm? Williams, p. 19

39. 39 Conduction Heat transfer due to collision of molecules. Conduction warms the bottom of the pan! Conductivity - rate of heat transfer across a 1 cm thick slab of material if one side is kept 1 o C warmer than the other Do a Cheap Experiment: Touch metal on your chair! 1 cm Metal WaterAir Heat Transfer 1oC1oC 0oC0oC

40. 40 Heat Conductivity

41. 41 Specific Heat Capacity Heat required to raise temperature of 1 gm of substance 1 o C. Metal has lower heat capacity than water!

42. 42 Convection Heat transfer due to vertical exchange of mass Occurs in fluids (liquids, gases) because of gravity Warm, buoyant air rises - Cool, dense air sinks Convection warms top of liquid! Warm Cool Warm Cool Warm Cool heat below - convectionheat side - convectionheat top - no convection gravity

43. 43 Convection Movies 2D Convection Tank Animation2D Convection Tank Animation  2D Convection Model Ra=10**6 2D Convection Model Ra=10**7 IC1 2D Convection Model Ra=10**7 IC2 3D Rayleigh-Benard Convection Model3D Rayleigh-Benard Convection Model 

44. 44 Energy States and Water Phases water molecules are tightly packed in a crystal alignment that prevents them from changing shape LOW ENERGY STATE attractive forces btw molecules weaken and individual molecules can move around each other, but they can not break away SLIGHTLY HIGHER ENERGY STATE water molecules move very rapidly and are not bound together EXTEMELY HIGH ENERGY STATE Small Energy Change Large Energy Change SOLIDLIQUIDVAPOR

45. 45 Latent Heat Ahrens, p 28 Weak attraction between molecules +540 cal/gm +80 cal/gm -540 cal/gm -80 cal/gm -620 cal/gm +620 cal/gm Strong attraction between molecules Some attraction More Ordered Phase Less Ordered Phase Surrounding air warms Surrounding air cools

46. 46 Modes of Heat Transfer Williams, p. 19 Latent Heat

47. 47 Take Home Points Heat-Energy transfer due to temperature differences Three modes of heat transfer Conduction – molecule to molecule Convection – transport of fluid Radiation – electromagnetic waves Next lecture! Latent Heat – energy of phase changes

48. 48 Next Class Assignment Radiation Reading - Ahrens 3rd: 30-42 4th: 30-42 5th: 30-42 Homework01 - D2L (Due Monday Jan 25 th ) 3rd-Pg 52: 2.7, 9, 10, 11, 12 4th-Pg 52: 2.7, 9, 10, 11, 12 5th-Pg 52: 2.7, 9, 10, 11, 12