Sept 17

1. Sept 17 • Today • Date of Midterm #1: Wed. Oct 1st • also Term Paper Topics due • Weather Review – • Weather Maps and Isopleths • Next Week – Sept 22 & 24 • Humidity, Condensation, Fog, Clouds, Precip (Chp 4 & 5)

2. Weather Review

3. Weather Review

4. Weather Review

5. Weather Review

6. Weather Review • Computer Models (aka “progs”) • Simulation of the atmosphere • Begin with initial conditions • Temperature • Moisture • Pressure • Wind • Apply atmospheric physics, thermodynamics, chemistry • Press “PLAY” • Simulates conditions into the future

18. Weather Review

20. Weather Symbols and Maps

21. Station model 021 80 -23 63

22. Weather Symbols

23. Sky Symbols

24. Wind Symbols

25. Pressure Tendency

26. Station model 80 021 -23 63

27. Station model 80 021 -23 63 Temperature Surface: ºF Upper air: ºC

28. Station model 021 80 -23 63 Dew point temperature Surface: ºF Upper air: ºC

29. Station model 021 80 -23 63 Totalsky cover ** Depicted by shading in circle

30. Station model 021 80 -23 63 Current weather conditions ** If blank, “no weather”

31. Station model 80 021 -23 63 Wind direction – of wind toward center

32. Station model 80 021 -23 63 Wind speed Long barb = 10 knots Short barb = 5 knots Flag = 50 knots ** Notice range of wind speeds (i.e., 28-32 knots)

33. Station model 021 80 -23 63 Sea level pressure **If first number is 5 or greater, then place 9 in front --Otherwise, place 10 in front **Place decimal point between last two numbers

34. Station model 021 80 -23 63 Change in surface pressure during last 3 hours ** In tenths of mb ** Line describes how pressure changes over time from left to right

35. Example 1 • Temperature: 76 ºF • Dew point: 65 ºF • Sky cover: Completely overcast • Current weather: Light rain • Wind direction and speed: Southwest at 15 knots • Sea level pressure: 995.3 mb • Pressure tendency: Increase of 1.6 mb; rising steadily 76 953 +16 65

36. Example 2 • Temperature: 10ºF • Dew point: 8ºF • Sky cover: 7/10 or 8/10 • Current weather: Snow shower • Wind direction and speed: North at 3-7 knots • Sea level pressure: 1010.5 mb • Pressure tendency: Decrease of 0.4 mb; falling, then steady

37. High & Low Pressure Systems • Air pressure Patterns are main organizing feature • Circulation in Northern Hemisphere • Clockwise around Highs (H) • CCW around Lows (L) • Clouds & Precip around Lows • Temperature patterns result from latitude, wind flow and cloud cover

38. Plotting Fronts • Boundary between Different Air Masses • Types of Fronts

39. Weather Maps

40. ISOPLETHS

41. Contour Maps

42. Contour Maps

43. Contour Maps

44. Weather Maps

45. Weather Maps

46. Weather Maps

47. Weather Maps

48. ISOTACHS

49. ISOHYET

50. ISOPLETHS • Connects all points that have the same value • Iso = equal (Greek) • Also called “Isolines” • Types • Isobar = pressure • Isallobar = pressure change per time • Isotherm = temperature • Isohyet = rainfall • Isonif = snowfall • isotach = wind speed