1. Aviation Weather Dynamically Speaking
+Materials: Beachball Globe, Cloud Charts
+Collect Previous HW
+ Came from Gleim and Kershner
+It’s a very dynamic environment
+Meteorology 101
+Course Philosophy – Concepts, not minutia
+“Weather Kills” – p 18 & 20 of Nall Report
Written for the Notre Dame Pilot Initiative
By the Pilots of the University of Notre Dame
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

2. Dedication John H. Fischer, Cadet Captain, CAP Grandmother
Prisoners of War / Missing In Action

3. Quote
Just remember, if you crash because of weather, your funeral will be held on a sunny day. –Layton A. Bennett
Weather kills pilots, a lot of them. These 75 minutes will be some of the most important of the course.

4. Roadmap Atmosphere & Global Circulation Weather & Climate
Clouds & Stability
Weather Forecasting

5. Lesson Plan Will learn Will be able to recite
Atmosphere & Global Circulation
Weather & Climate
Clouds & Stability
Weather Forecasting
Will be able to recite
Air Mass Types
Lapse Rates
Stages of Thunderstorm Development
Types of Fog & Clouds
Will be able to distinguish
Pictures of different cloud types

6. The Atmosphere & Global Circulation
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

7. Atmospheric Composition
Earth's atmosphere has a unique composition of gases when compared to that of the other planets in the solar system.

8. At greater altitudes, the same volume of air contains fewer molecules of the gases that make it up. This means that the density of air decreases with increasing altitude.

9. At 7 miles, or FL350, the air is only ¼ dense of what it was
At 7 miles, or FL350, the air is only ¼ dense of what it was. Hence, increased operating efficiency, less weather, and pressurization
The earth's atmosphere thins rapidly with increasing altitude and is much closer to the earth than most people realize.

10. Thermal Model of the Atmosphere
Show how it curves
Linear to the tropopause about 2 degrees C per 1000 feet
remains at –60 until outside the Ozone layer
For next slide
What makes the atmosphere change? What is the cause?
Wind caused by uneven heating

11. Sunlight Angle
On a global, yearly basis, the equatorial region of the earth receives more direct incoming solar radiation than the higher latitudes. As a result, average temperatures are higher in the equatorial region and decrease with latitude toward both poles. This sets the stage for worldwide patterns of prevailing winds, high and low areas of atmospheric pressure, and climatic patterns.
When you think of atmospheric changes, think heat.
Uneven heating creates wind and pressure areas.
Use Globe to show angle of sunlight

12. Global Wind Patterns
Hot air rises over the equator due to the fact that it is less dense.
This is called the intertropical convergence zone
This rising air cools as it rises resulting in precipitation in the region of the ITCZ.
The air then travels north and south at high altitude.
Use globe to describe in 3-d what is happening
Air Goes North and south to fill vacuum created by air filling in for rising air

13. Global Circulation With Globe, Coriolis
Seasons – Have kid stand on table as sun
Chris Columbus - trades
With Fan, demonstrate orthographic lifting
Coriolis with Globe

14. Global Wind Patterns
Hot air rises over the equator due to the fact that it is less dense.
The cooled air descends to reach the surface at about 24 ON and 24 OS of the equator.
This forms a high pressure area
The great deserts of the world are located in this high pressure area
Sahara, Saudi Arabia, Hawaii, Mexico
Go back to previous slide to show the effect.

15. Coriolis Effect
Demonstrate throwing a ball off of a merry go around.

16. An object in motion in the northern hemisphere appears to turn to the right.
An object in motion in the southern hemisphere appears to turn to the left.

17. Global Circ Pix
Explain Westerlies
Part of the generalized global circulation pattern of the earth's atmosphere. The scale of upward movement of air above the intertropical convergence zone is exaggerated for clarity. The troposphere over the equator is thicker than elsewhere, reaching a height of about 12 mi.

18. Air sinks over a high-pressure center that moves away from the center on the surface, veering to the right in the Northern Hemisphere to create a clockwise circulation pattern.
Air moves toward a low-pressure center on the surface, rising over the center. As air moves toward the low-pressure center on the surface, it veers to the left in the Northern Hemisphere to create a counterclockwise circulation pattern.
Pressure Areas
End Atmosphere & Circulation Section

19. Weather and Climate
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

20. Definition
Consider pix from ND
Weather is a description of the changeable aspects of the atmosphere, the temperature, rainfall, pressure, and so forth, at a particular time. These changes usually affect your daily life one way or another, but some of them seem more inconvenient than others.

21. Flying into Elkhart, Rwy 35
Notice the blade twist

22. Air Masses Polar air mass Tropical Air Mass Continental Air Mass
An air mass that moves from a cold region
Tropical Air Mass
An air mass that moves from a warm region
Continental Air Mass
Moves in from a land mass
Maritime Air Mass
Moves in from over an ocean
How have we defined these air masses then?

23. Air Mass Types Temperature/Moisture Hot Cold Wet Tropical Maritime
Polar Maritime
Dry
Tropical Continental
Polar Continental
Coldest temperatures = polar continental
Most Humid days = tropical maritime

24. Current Weather Notice Hurricane & how it got pushed out of the way
What goes here?
Get Current Chart at weather.com

25. Clouds and Stability
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

26. Types of Clouds Cumulus (heaped) Stratus (layered) Cirrus (curled)
Nimbus (rain)
What’s outside today? Yesterday? Tomorrow?
Owl

27. How a Cloud Forms Temperature and Dewpoint Converge
Water Condenses on Particles (Dirt, Dust, Smoke)
Fog is a cloud very near to the surface
Guess Bridge?
Owl

28. Precipitation
Precipitation is water in the liquid or solid form that returns to the surface of the earth. The precipitation you see here is liquid, and each raindrop is made from billions of the tiny droplets that make up the clouds. The tiny droplets of clouds become precipitation by merging to form larger droplets or by the growth of ice crystals that melt while falling.
Note Verga – precipitation that does not hit the ground
New Mexico Desert – Why is verga so common there?

29. Condensation Nucleus (0.2 microns)
Average Cloud Droplet (20 microns)
Large Cloud Droplet (100 microns)
Drizzle Droplet (300 microns)
Average Rain Drop (2000 microns)
Flying through a cloud is like flying through air, same consistency
Close the Vents when you fly through a cloud
This figure compares the size of the condensation nuclei to the size of typical condensation droplets. Note that 1 micron is 1/1,000 mm.

30. Stability Air may be: Unstable (vertically) Cumulus clouds
Stratus clouds

31. Cumulus
Fair weather
Fair weather

32. Lapse Rate
Avg Lapse Rate = 2 deg C (3.5 deg F) / 1K !!! (Environment)
In Thermal, it is 3 deg C (4.4 deg F) / 1K
B/C of heat & expansion
Who knows what 15 C = ? F (59 F)
Got that math, now we start hauling through 60 pictures
The average lapse rate (rate of cooling) is 2° C per 1,000 feet or 3.5° F per 1,000 feet
In order to calculate the base of thermal driven cumulus clouds, divide the temperature / dewpoint spread by the lapse rate (4.4 ° F per 1,000 feet )

33. Altocumulus
Mackerel sky

34. Altocumulus at Sunrise
We’ll see later that this means bad weather tomorrow
Altocumulus at Sunrise

35. Temperature Inversion
Refer to previous slide on stability

36. Note inversion and fog found below 100 feet

37. Fog is a cloud very near to the surface

38. Types of Fog Radiation (ground) fog Advection fog
Requires wind
Warm air over cold land or water
Upslope (orographic) fog
Steam fog
Lake or ocean source of water
Cold air over warm water
Precipitation fog (rain fog)
Show slides of different types of Fog

39. Radiation Fog From the Air Radiation found on calm nights,
often under an inversion,
Farmer’s Field – Driving on a clear road w/fog on sides

40. Advection Fog
Three times now we’ve seen this picture. Isn’t it beautiful? Not if you’re going into SFO!
Warm air over cold land or water

41. Upslope Fog
Orographic Fog = Why mountains are often in clouds, air gets squeezed and moisture condenses
Which way is wind blowing?

42. Upslope Fog

43. Steam Fog That’s a lake in the background
Most types of fog form in stable atmospheric conditions. The exception is steam fog, shown in this picture of Maligne Lake, Alberta, Canada, just after sunrise in late summer. The land cools off overnight while the water retains heat from the summer. As the cooled air slips over the lake, heat and moisture are added from below, resulting in a fog that twists and writhes-- hence the term "steam fog".

44. Orchard
Orchards try to eliminate the inversion
Anyone from FL?
Fans like this one are used to mix the warmer, upper layers of air with the cooling air in the orchard on nights when frost is likely to form.

45. Ice possible in the tops
Stratocumulus
Ice possible in the tops

46. Stratocumulus from above

47. Stratocumulus Red sky in the morning, sailors take warning
Red sky at night, sailors’ delight—only applies in the tropics

48. Types of Clouds Cumulus (piled up) Stratus (layered) Cirrus (curled)
Nimbus (rain)
Review cumulus and stratus

49. Cirrus
Overrunning moisture

50. Cirrostratus
Moisture increasing

51. Cirrostratus Hazy circle round the moon
Means that rain is coming soon!

52. Cirrostratus
Condensation Trails (Contrails)

53. Cirrocumulus
Warm front is getting closer

54. Thunderstorms Thunderstorms require T-storms always have lightning
Unstable air
Moisture
Lifting mechanism
T-storms always have lightning
Thunder is the sound of lightning
T-storms are reported when thunder is heard
Only true for manned observation posts
Automatic Reporting (AWOS) detects lightning discharge
Note reporting criteria OWL
Lightning is not that dangerous to an airplane, turbulence is
No such thing as heat lightning
Proper way to avoid getting struck by lightning = arms to knees
Boy Scout Tip of the Day

55. Updrafts from thermals
Three stages in the life of a thunderstorm cell. (A) The cumulus stage begins as warm, moist air is lifted in an unstable atmosphere. All the air movement is upward in this stage.

56. Updrafts and downdrafts, starts when rain touches the ground
(B) The mature stage begins when precipitation reaches the ground. This stage has updrafts and downdrafts side by side, which create violent turbulence.

57. Only downdrafts
“There is no reason to fly through a thunderstorm in peacetime.” –Sign over squadron ops desk at Davis-Monthan AFB, AZ
(C) The final stage begins when all the updrafts have been cut off, and only downdrafts exist. This cuts off the supply of moisture, and the rain decreases as the thunderstorm dissipates. The anvil-shaped top is a characteristic sign of this stage.

58. Lightning
Develop charge from the friction between rising and falling air currents.
Like scuffing across the floor and touching a metal ball
Different parts of a thunderstorm cloud develop centers of electric charge. Lightning is a giant electric spark that discharges the accumulated charges.

59. Thunderstorms Types of thunderstorms Air mass Frontal
Upslope (orographic)
Air Mass can often be sporadic and sparse but can reach upwards of FL600
Frontal are usually more organized often as squall lines ahead of cold fronts, usually more powerful
Upslope often are only a problem on the upwind side while the lee remains in cool dry air (Sierra Nevadas or Cascades)

60. Hail
Hail most commonly thrown up to many miles from the anvil head of a t-storm
These hailstones fell from a thunderstorm in Iowa, damaging automobiles, structures, and crops.

61. Cumulonimbus Distance to a Storm Thunderstorm Nimbus means rain
5 sec per mile at the speed of sound
Thunderstorm

62. Bad Idea
Thunderstorm from an MD-80 at 30,000 feet

63. Cumulonimbus From Space

64. Boundaries between air masses = fronts
Types of Fronts
Cold
Warm
Stationary
Occluded
These are the four types of fronts

65. Weather Fronts Front A boundary between two different air masses
Cold Front
When a cold air mass moves into a warmer area, displacing the warm air mass
Provides lift to adiabatically cool the warm air, resulting in towering cumulus and thunderclouds.
Blue Triangles on Charts
Cold Air pushes under Warm Air forcing it upwards
Squall lines are areas of thunderstorms about miles ahead of a cold front

66. A cold air mass is similar to a huge, flattened bubble of cold air that moves across the land. The front is the boundary between two air masses, a narrow transition zone of mixing.
A front is represented by a line on a weather map, which shows the location of the front at ground level.
Cold Front Pix
See Kershner Chapter 22 for outstanding cross-sections of fronts
Notice how the front aloft is many miles behind where it is on the ground

67. When a warm air mass moves into an area, displacing the cold air mass
Warm Front
When a warm air mass moves into an area, displacing the cold air mass
A gently sloping front as the Warm air moves over top of the cooler air.
Stationary Front
When the edge of a front ceases to advance
Red Semicircles denote Warm
Red and Blue denotes Stationary

68. Warm Front Pix
An idealized warm front, showing a warm air mass overriding and pushing cold air in front of it. Notice that the overriding warm air produces a predictable sequence of clouds far in advance of the moving front.

69. Occluded Front One that has been lifted completely off the ground
Has a low pressure center and cyclonic activity
Purple Triangles
Often caused by a fast moving cold front overrunning a warm front

70. Show how weather develops in next three slides

72. Take a look at these three again.

73. Cyclones L
Cyclone
A low pressure area with winds moving into the low pressure area and being forced upward.
Friction and the Coriolis effect cause the air to move to the right of the direction of movement.
Anticyclone
A high pressure center
Lows are usually in Red, Highs usually in Blue
A very small L means a tropical depression.
A severe tropical depression is a tropical storm/hurricane marked with a squiggle H

74. Hurricane John
This is a satellite photo of hurricane John, showing the eye and counterclockwise motion

75. Storm Tracks
Note SE track, trough tracks, and Alberta Clippers
Cyclonic storms usually follow principal storm tracks across the continental United States in a generally easterly direction. This makes it possible to predict where the low-pressure storm might move next.

76. Weather Forecasting “Weather forecasts are horoscopes with numbers. “
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

77. Computer Models
Note different models on left side

78. Weather Predictions
Weather predictions are based on information about air masses, fronts, and associated pressure systems in an area.
This information is used to produce a model of behavior for weather using a computer.
Many models are used and then summarized when the different models agree fairly closely to a model of the weather.
The closer the forecast is the more accurate it will be.
Computes have taken an artform and forced a science upon it. A science that does not fit well
I laugh at the 10 day forecasts
Why do you think the weather channel has the money barometer (it’s easier to forecast the stock market!) They seem to have trouble predicting the past!

79. Surface Pressure/Precipitation Plot

80. Predicted
Notice no storm in OK, weakened storm in Ontario and dissipating cold front on the Atlantic Coast
Actual

81. Forecast for today
????????? Add today’s forecast

82. Supercomputers
Supercomputers make routine weather forecasts possible by solving mathematical equations that describe changes in a mathematical model of the atmosphere. This "fish-eye" view was necessary to show all of this Cray supercomputer at CERN, the European Center of Particle Physics.

83. Example of Atmospheric Refraction
Home of the Flyin’ Irish!
Aviation Weather, last slide
Skyspotter HW due on THU (print certificate, or something)
Where’s the pot of gold?