Table of Contents
Chapter 1. Introduction ........................................................................................................... 1-1
Part 1: Overview of the United States Aviation Weather Service Program and Information
Chapter 2. Aviation Weather Service Program ..................................................................... 2-1
2.1 Introduction ............................................................................................................................... 2-1
2.2 National Oceanic and Atmospheric Administration (NOAA) ................................................... 2-2
2.3 Federal Aviation Administration (FAA) ................................................................................... 2-4
2.4 Department of Defense (DOD) .................................................................................................. 2-5
2.5 Commercial Weather Information Providers ............................................................................. 2-5
Chapter 3. Overview of Aviation Weather Information ......................................................... 3-1
3.1 Introduction ............................................................................................................................... 3-1
3.2 Use of Aviation Weather Information ....................................................................................... 3-2
3.3 Obtaining Weather Information ................................................................................................. 3-3
3.4 Overview of Aviation Weather Products ................................................................................... 3-7
Part 2: Weather Theory and Aviation Hazards
Chapter 4. The Earth’s Atmosphere ....................................................................................... 4-1
4.1 Introduction ............................................................................................................................... 4-1
4.2 Composition ............................................................................................................................... 4-2
4.3 Vertical Structure ....................................................................................................................... 4-3
4.4 The Standard Atmosphere ......................................................................................................... 4-5
Chapter 5. Heat and Temperature .......................................................................................... 5-1
5.1 Introduction ............................................................................................................................... 5-1
5.2 Matter ........................................................................................................................................ 5-2
5.3 Energy ........................................................................................................................................ 5-2
5.4 Heat ............................................................................................................................................ 5-2
5.5 Temperature ............................................................................................................................... 5-2
5.6 Heat Transfer ............................................................................................................................. 5-4
5.7 Thermal Response ..................................................................................................................... 5-8
5.8 Temperature Variations with Altitude ..................................................................................... 5-11
Chapter 6. Water Vapor ........................................................................................................... 6-1
6.1 Introduction ............................................................................................................................... 6-1
6.2 The Hydrologic Cycle ............................................................................................................... 6-2
6.3 Saturation ................................................................................................................................... 6-3
6.4 Relative Humidity ...................................................................................................................... 6-4
6.5 Dewpoint ................................................................................................................................... 6-4
6.6 Temperature-Dewpoint Spread (Dewpoint Depression) ........................................................... 6-4
6.7 Change of Phase ........................................................................................................................ 6-5
Chapter 7. Earth-Atmosphere Heat Imbalances .................................................................... 7-1
7.1 Introduction ............................................................................................................................... 7-1
7.2 The Earth-Atmosphere Energy Balance .................................................................................... 7-2
7.3 Heat Imbalances Between Earth’s Surface and the Atmosphere ............................................... 7-3
7.4 Heat Imbalance Variations with Latitude .................................................................................. 7-5
7.5 Seasons ...................................................................................................................................... 7-6
7.6 Diurnal Temperature Variation .................................................................................................. 7-7
Chapter 8. Atmospheric Pressure and Altimetry .................................................................. 8-1
8.1 Introduction ............................................................................................................................... 8-1
8.2 Atmospheric Pressure ................................................................................................................ 8-2
8.3 Density ....................................................................................................................................... 8-7
8.4 Altimetry .................................................................................................................................. 8-10
Chapter 9. Global Circulations and Jet Streams ................................................................... 9-1
9.1 Introduction ............................................................................................................................... 9-1
9.2 Non-Rotating Earth Circulation System .................................................................................... 9-2
9.3 Rotating Earth Circulation System ............................................................................................ 9-2
9.4 Jet Streams ................................................................................................................................. 9-3
Chapter 10. Wind .................................................................................................................... 10-1
10.1 Introduction ............................................................................................................................. 10-1
10.2 Naming of the Wind ................................................................................................................ 10-2
10.3 Forces That Affect the Wind ................................................................................................... 10-2
10.4 Upper Air Wind ....................................................................................................................... 10-6
10.5 Surface Wind ........................................................................................................................... 10-7
10.6 Local Winds ............................................................................................................................. 10-8
10.7 Adverse Winds ...................................................................................................................... 10-16
Chapter 11. Air Masses, Fronts, and the Wave Cyclone Model ......................................... 11-1
11.1 Introduction ............................................................................................................................. 11-1
11.2 Air Masses ............................................................................................................................... 11-2
11.3 Fronts ....................................................................................................................................... 11-4
11.4 The Wave Cyclone Model ....................................................................................................... 11-9
11.5 Dryline ................................................................................................................................... 11-11
Chapter 12. Vertical Motion and Clouds .............................................................................. 12-1
12.1 Introduction ............................................................................................................................. 12-1
12.2 Vertical Motion Effects on an Unsaturated Air Parcel ............................................................ 12-2
12.3 Vertical Motion Effects on a Saturated Air Parcel .................................................................. 12-3
12.4 Common Sources of Vertical Motion ...................................................................................... 12-5
12.5 Cloud Forms ............................................................................................................................ 12-8
12.6 Cloud Levels ............................................................................................................................ 12-8
Chapter 13. Atmospheric Stability ....................................................................................... 13-1
13.1 Introduction ............................................................................................................................. 13-1
13.2 Using a Parcel as a Tool to Evaluate Stability ......................................................................... 13-2
13.3 Stability Types ......................................................................................................................... 13-2
13.4 Processes That Change Atmospheric Stability ........................................................................ 13-7
13.5 Measurements of Stability ....................................................................................................... 13-9
13.6 Convection ............................................................................................................................. 13-11
13.7 Summary ................................................................................................................................ 13-11
Chapter 14. Precipitation ....................................................................................................... 14-1
14.1 Introduction ............................................................................................................................. 14-1
14.2 Necessary Ingredients for Formation ....................................................................................... 14-2
14.3 Growth Process ........................................................................................................................ 14-2
14.4 Precipitation Types .................................................................................................................. 14-3
Chapter 15. Weather Radar ................................................................................................... 15-1
15.1 Introduction ............................................................................................................................. 15-1
15.2 Principles of Weather Radar .................................................................................................... 15-2
Chapter 16. Mountain Weather ............................................................................................. 16-1
16.1 Introduction ............................................................................................................................. 16-1
16.2 Mountain Waves and Adverse Winds ..................................................................................... 16-2
16.3 Mountain/Valley Breezes and Circulation ............................................................................. 16-17
16.4 Mountain/Valley Fog ............................................................................................................. 16-17
16.5 Upslope Fog ........................................................................................................................... 16-17
16.6 Mountain Obscuration ........................................................................................................... 16-17
16.7 Mountain Turbulence ............................................................................................................ 16-17
16.8 Mountain Icing ...................................................................................................................... 16-17
16.9 Density Altitude ..................................................................................................................... 16-17
Chapter 17. Tropical Weather ............................................................................................... 17-1
17.1 Introduction ............................................................................................................................. 17-1
17.2 Circulation ............................................................................................................................... 17-2
17.3 Transitory Systems .................................................................................................................. 17-7
Chapter 18. Weather and Obstructions to Visibility ........................................................... 18-1
18.1 Introduction ............................................................................................................................. 18-1
18.2 Low Ceiling and Mountain Obscuration ............................................................................... 18-12
Chapter 19. Turbulence ......................................................................................................... 19-1
19.1 Introduction ............................................................................................................................. 19-1
19.2 Causes of Turbulence .............................................................................................................. 19-2
Chapter 20. Icing .................................................................................................................... 20-1
20.1 Introduction ............................................................................................................................. 20-1
20.2 Supercooled Water .................................................................................................................. 20-2
20.3 Structural Icing ........................................................................................................................ 20-2
20.4 Engine Icing ............................................................................................................................. 20-7
20.5 Additional Information ............................................................................................................ 20-8
Chapter 21. Arctic Weather ................................................................................................... 21-1
21.1 Introduction ............................................................................................................................. 21-1
21.2 Climate, Air Masses, and Fronts .............................................................................................. 21-2
21.3 Arctic Peculiarities .................................................................................................................. 21-4
21.4 Arctic Weather Hazards ........................................................................................................... 21-4
Chapter 22. Thunderstorms .................................................................................................. 22-1
22.1 Introduction ............................................................................................................................. 22-1
22.2 Necessary Ingredients for Thunderstorm Cell Formation ....................................................... 22-2
22.3 Thunderstorm Cell Life Cycle ................................................................................................. 22-2
22.4 Thunderstorm Types ................................................................................................................ 22-3
22.5 Factors that Influence Thunderstorm Motion .......................................................................... 22-5
22.6 Thunderstorm Terminology ..................................................................................................... 22-6
22.7 Hazards .................................................................................................................................... 22-7
22.8 Thunderstorm Avoidance ...................................................................................................... 22-20
Chapter 23. Space Weather ................................................................................................... 23-1
23.1 Introduction ............................................................................................................................. 23-1
23.2 The Sun—Prime Source of Space Weather ............................................................................. 23-2
23.3 The Sun’s Energy Output and Variability ............................................................................... 23-2
23.4 Sunspots and the Solar Cycle .................................................................................................. 23-2
23.5 Solar Wind ............................................................................................................................... 23-2
23.6 Solar Eruptive Activity ............................................................................................................ 23-3
23.7 Geospace .................................................................................................................................. 23-3
23.8 Galactic Cosmic Rays (GCR) .................................................................................................. 23-4
23.9 Geomagnetic Storms ................................................................................................................ 23-4
23.10 Solar Radiation Storms ............................................................................................................ 23-4
23.11 Ionospheric Storms .................................................................................................................. 23-5
23.12 Solar Flare Radio Blackouts .................................................................................................... 23-5
23.13 Effects of Space Weather on Aircraft Operations ................................................................... 23-6
Part 3: Technical Details Relating to Weather Products and Aviation Weather Tools
Chapter 24. Observations ..................................................................................................... 24-1
24.1 Introduction ............................................................................................................................. 24-1
24.2 Surface Observations ............................................................................................................... 24-2
24.3 Automated Surface Observing System (ASOS) and Automated Weather Observing
System (AWOS) ...................................................................................................................... 24-2
24.4 Aviation Routine Weather Report and Aviation Selected Special Weather Report ................ 24-5
24.5 Aircraft Observations and Reports ........................................................................................ 24-26
24.6 Radar Observations ................................................................................................................ 24-36
24.7 Satellite Observations ............................................................................................................ 24-45
24.8 Upper Air Observations ......................................................................................................... 24-51
24.9 Aviation Weather Cameras .................................................................................................... 24-53
Chapter 25. Analysis .............................................................................................................. 25-1
25.1 Introduction ............................................................................................................................. 25-1
25.2 Weather Charts ........................................................................................................................ 25-2
25.3 Upper Air Analysis ................................................................................................................ 25-18
25.4 Freezing Level Analysis ........................................................................................................ 25-23
25.5 Icing Analysis (Current Icing Product (CIP)) ........................................................................ 25-23
25.6 Turbulence [Graphical Turbulence Guidance (GTG)] Analysis ........................................... 25-24
25.7 Real-Time Mesoscale Analysis (RTMA) .............................................................................. 25-24
Chapter 26. Advisories .......................................................................................................... 26-1
26.1 Introduction ............................................................................................................................. 26-1
26.2 Significant Meteorological Information (SIGMET) ................................................................ 26-2
26.3 Airmen’s Meteorological Information (AIRMET) ................................................................ 26-15
26.4 Center Weather Advisory (CWA) ......................................................................................... 26-20
26.5 Volcanic Ash Advisory (VAA) ............................................................................................. 26-23
26.6 Aviation Tropical Cyclone Advisory (TCA) ......................................................................... 26-26
26.7 Space Weather Advisory ....................................................................................................... 26-28
26.8 Low-Level Wind Shear (LLWS)/Microburst Advisories ...................................................... 26-33
26.9 Airport Weather Warning (AWW) ........................................................................................ 26-33
Chapter 27. Forecasts ........................................................................................................... 27-1
27.1 Introduction ............................................................................................................................. 27-1
27.2 Winds and Temperatures Aloft ................................................................................................ 27-3
27.3 Terminal Aerodrome Forecast (TAF) ...................................................................................... 27-6
27.4 Aviation Surface Forecast and Aviation Clouds Forecast ..................................................... 27-22
27.5 Area Forecasts (FA) ............................................................................................................... 27-24
27.6 Alaska Graphical Forecasts ................................................................................................... 27-27
27.7 World Area Forecast System (WAFS) .................................................................................. 27-32
27.8 Significant Weather (SIGWX) .............................................................................................. 27-35
27.9 Short-Range Surface Prognostic (Prog) Charts ..................................................................... 27-48
27.10 Upper Air Forecasts ............................................................................................................... 27-50
27.11 Freezing Level Forecast Graphics ......................................................................................... 27-53
27.12 Forecast Icing Product (FIP) .................................................................................................. 27-53
27.13 Graphical Turbulence Guidance (GTG) ................................................................................ 27-54
27.14 Cloud Tops ............................................................................................................................ 27-55
27.15 Localized Aviation Model Output Statistics (MOS) Program (LAMP) ................................ 27-55
27.16 Additional Products for Convection ...................................................................................... 27-56
27.17 Route Forecast (ROFOR) ...................................................................................................... 27-64
27.18 Aviation Forecast Discussion (AFD) ..................................................................................... 27-65
27.19 Meteorological Impact Statement (MIS) ............................................................................... 27-66
27.20 Soaring Forecast .................................................................................................................... 27-66
27.21 Balloon Forecast .................................................................................................................... 27-67
Chapter 28. Aviation Weather Tools .................................................................................... 28-1
28.1 Introduction ............................................................................................................................. 28-1
28.2 Graphical Forecasts for Aviation (GFA) Tool ......................................................................... 28-2
28.3 FAA Flight Service’s Interactive Map .................................................................................... 28-2
Appendices
Appendix A. Cloud Types ...................................................................................................... A-1
A.1 High Clouds .............................................................................................................................. A-1
A.2 Middle Clouds .......................................................................................................................... A-3
A.3 Low Clouds ............................................................................................................................... A-7
Appendix B. Standard Conversion Chart ............................................................................. B-1
Appendix C. Density Altitude Calculation ............................................................................ C-1
Appendix D. Special Terminal Operation Procedures (STOP) for Operations in a
Noncontiguous State .............................................................................................................. D-1
D.1 Introduction .............................................................................................................................. D-1
D.2 Weather Information ................................................................................................................. D-1
D.3 Airport Data .............................................................................................................................. D-5
D.4 Flight Planning ......................................................................................................................... D-6
D.5 Preflight Planning and Briefing to STOP Airport .................................................................... D-8
D.6 En Route, Flight Monitoring, and Communications ................................................................. D-8
D.7 Destination Approach and Arrival .......................................................................................... D-10
D.8 Departure Procedures From a STOP Airport .......................................................................... D-10
D.9 Training for Dispatchers, Flight Followers, and Flightcrew .................................................. D-11
D.10 Approval ................................................................................................................................. D-12
D.11 Compliance Monitoring, Quality Assurance (QA), and Auditing .......................................... D-13
Appendix E. Abbreviations, Acronyms, and Initialisms ...................................................... E-1
Appendix F. Units of Measurement ....................................................................................... F-1
Appendix G. Websites ............................................................................................................ G-1