Fig. 3-CO, p. 54

1. Fig. 3-CO, p. 54

2. SEASONAL and DAILY TEMPERATURES • REASONS for the SEASONS • We are a space object obeying the Laws of Gravity, orbiting the sun in 365.2422 days. • Our orbit is elliptical having an eccentricity of 0.017. (Zero is a perfect circle) • The earth is inclined to the plane of its orbit by 23 1/2 degrees.

3. Fig. 3-1, p. 56

4. Fig. 3-2a, p. 56

5. Fig. 3-2b, p. 56

6. Fig. 3-3, p. 57

7. Fig. 3-4, p. 58

8. Fig. 3-5, p. 58

9. Fig. 3-6, p. 58

10. Fig. 3-7, p. 59

11. Table 3-1, p. 60

12. When does a Season Begin? • Season AstronomicallyMeteorologically • Spring March 20 March 1 • Summer June 21 June 1 • Autumn Sept. 22 Sept 1 • Winter Dec. 21 Dec 1 • Latitudes Tropic of Cancer + 23.5o • Tropic of Capricorn - 23.5o • Arctic Circle +66.5 o Anarctic Circle -66.5o.

13. Fig. 3-8, p. 61

14. Fig. 1, p. 62

15. Hemispheric Seasonal Variations • The sun is located at one focus of an ellipse, so one half of the earth’s orbit is longer than the other. • Northern Hemisphere --Summer is a week longer than Winter. Reversed in the SH. • Earth is closer to the sun (3 Million Miles) in NH so winters are slightly warmer. More water around SH moderates their winters.

16. Fig. 3-9, p. 62

17. Local Seasonal Variations • South sides of hills -- more sunlight • Vinyards , Solar Collectors • Clear sky regions -- drier less vegetation • Southside-Large windows for winter sun • North sides of hills --less sunlight • Ski Lodges, Summer porches and patios • Northside--Bedrooms for better sleeping

18. Fig. 3-10, p. 63

19. Solar Collector Angle Settings • Location of collector is south facing roof • Angle of collector should be an average for the winter sun maximum altitude. • Boone Latitude is +36.2o So lowest max is on Dec 21st. 36.2 +23.5 = 59.7o or 30.3o • The highest max is on March 20th. So the value is 36.2 - 0 = 36.2o or 53.8o The average is (53.8 + 30.3)/2 = 42o . In general the angle is ~ Latitude + 6o .

20. Fig. 2, p. 64

21. Daily Temperature Variations • The earth spins one revolution on its rotational axis in 24 hours. This is not quite 24 hours and so a second is added when needed on either Jan 1st or July 1st. Last century about 54 seconds were added. This amounts to the day lengthening by ~ 1.5 ms/century. • The lengthening is caused by tidal friction mostly by the Moon and lesser by the Sun.

22. Cause of Temperature Variation • Daytime Warming -- lack of wind causes large temperature variation. • Nightime Cooling -- radiation cooling • radiation inversions, thermal belts. Wind effects. • Crop Protection -- orchard heaters, wind machines, sprinkling water.

23. Fig. 3-11, p. 65

24. Fig. 3-12, p. 65

25. Fig. 3-13, p. 65

26. Table 1, p. 66

27. Fig. 3, p. 66

28. Radiation Inversion • At night the ground loses temperature quickly by radiation, this causes a radiation temperature inversion. • The inversion is more pronounced on a dry clear calm night.

29. Fig. 3-14, p. 67

30. Fig. 3-15, p. 67

31. Thermal Belt • Oin mid-latitudes on dry cold clear nights a valley between high hills or mountains will have cold air slowly falling into basins or valleys. Thus the nearby hillsides will be warmer and are less likely to be below freezing. Thus orchards planted in this region about 100-300 meters above are less likely to freeze. Above this height there will be freezing temperatures.

32. Fig. 3-16, p. 68

33. Table 2, p. 69

34. Fig. 3-17, p. 70

35. Fig. 3-18, p. 70

36. Fig. 3-19, p. 70

37. The Controls of Temperature • Latitude -- determines the intensity of solar radiation and the length of daylight hours • Land and water distribution -- large amounts of land with its low specific heat leads to colder regions in winter and hotter regions in the summer. Water with its high specific heat moderates the temperature.

38. The Controls of Temperature • Ocean currents -- warm currents transports energy poleward, cold currents transport cold water equatorward. • Elevation -- the lapse rate cools these regions.

39. Fig. 3-20, p. 72

40. Fig. 3-21, p. 72

41. Air Temperature Data • The greatest daily (diurnal) variation in temperatures is at the ground level. • The largest range of variation is in the deserts. Less vapor and more radiation. • Less change in very humid climates. • Cities have urban heat island effect. Lot of asphalt which absorbs more radiation. More energy used all day and evening.

42. Fig. 3-22, p. 73

43. Fig. 3-23, p. 74

44. Fig. 3-24, p. 74

45. NORMAL CLIMATE VALUES • Normal values of all climate parameters are based on a 30 year running average. This average is changed every decade. • The present normal values are based on the years 1971-2000. • Normals are prepared for local cooperative weather stations, airports, state, and national averages.

46. NORMAL CLIMATE VALUES • Normal climate values are found for: • Temperatures avg,high,low and extremes. • Annual Heating and Cooling Degree Days, • Rainfall • Snowfall • Freeze Data • Growing Degree Units

47. Fig. 4, p. 75

48. HEATING AND COOLINGDEGREE DAYS • Heating degree days is a quantity which approximates how much energy must be added to a structure each day to raise the temperature to a base level (usually 65oF). • Mathematically this is: • HDD = (65 - (Tmax + Tmin)/2)x 1 day. • Annual values are summed for 365 days: • HDD = Σ(65 - (Tmax + Tmin)/2).

49. HEATING AND COOLINGDEGREE DAYS • Cooling degree days is a quantity which approximates how much energy must be removed from a structure each day to lower the temperature to a base level (usually 65oF). Mathematically: • CDD = ((Tmax + Tmin)/2) – 65)x 1 day. • Annual values are summed for 365 days: • CDD = Σ((Tmax + Tmin)/2) – 65)

50. Fig. 3-25, p. 76