Study guide
2.4 Earth Motion, Regional Weather, Local Winds, and Water Phase Changes
FAA Aircraft Dispatcher Certificate ADX
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1 Chapter 1: Regulations, Certification & Operational Control
1.1 Part 65 Subpart C: Certification, Eligibility & Currency 1.2 Operational Control & Dispatcher-PIC Joint Responsibility 1.3 Domestic, Flag & Supplemental Operations Framework 1.4 Dispatch Release Elements, Signatures & Recordkeeping 1.5 Regulations, Manuals, Crew Qualifications, and Source Control
2 Chapter 2: Atmospheric Physics, Pressure Systems & Fronts
2.1 Atmospheric Structure, Standard Atmosphere & Altimetry 2.2 Air Masses, Frontal Systems & Frontogenesis 2.3 Atmospheric Stability, Lapse Rates & Cloud Formation 2.4 Earth Motion, Regional Weather, Local Winds, and Water Phase Changes
3 Chapter 3: Aviation Weather Hazards & Severe Weather Avoidance
3.1 Structural and Induction Icing: Types, Accretion & Operations 3.2 Thunderstorms, Squall Lines, Microbursts & Low-Level Windshear 3.3 Clear Air Turbulence (CAT), Mountain Waves & Jet Streams 3.4 Low Ceilings, Fog Types & Visibility Restrictions 3.5 Hurricanes, Typhoons, Tornadoes, and Tropical Dispatch Hazards
4 Chapter 4: Weather Observations, Forecasts & Advisories Decoding
4.1 METAR and SPECI Surface Observations: Decoding & Operations 4.2 Terminal Aerodrome Forecasts (TAF): Groups & Timing 4.3 Pilot Weather Reports (PIREP): Coding, Severity & Urgent Alerts 4.4 In-Flight Advisories: AIRMETs, SIGMETs & Convective SIGMETs 4.5 Weather Collection, NWS Facilities, GFA, and EWINS
5 Chapter 5: Aviation Weather Charts & Upper-Air Analysis
5.1 Surface Analysis & Radar Summary Charts 5.2 Constant Pressure Analysis & Winds Aloft (FB) 5.3 Significant Weather Prognostic Charts (SIGWX) 5.4 Satellite Imagery, Moisture-Stability Analysis, and Forecast Integration
6 Chapter 6: Air Navigation, Airspace Architecture & Route Structure
6.1 National Airspace System: Classes, Rules & Special Use 6.2 Ground-Based Navigation Aids & Standard Service Volumes 6.3 Area Navigation (RNAV), GNSS/GPS, PBN & RNP Fundamentals 6.4 En Route Airways, SIDs, STARs & Chart Interpretation 6.5 Earth Coordinates, UTC, Chart Projections, and Flight Instruments 6.6 North Atlantic, Pacific, RVSM, and Global Navigation Differences
7 Chapter 7: Instrument Approaches, Minimums & Airport Operations
7.1 Precision Approach Systems: ILS Categories & Tolerances 7.2 Non-Precision Approaches, RNAV & Decision Minimums (MDA/DA) 7.3 Takeoff Minimums, Lower-Than-Standard & Takeoff Alternates 7.4 Holding Procedures: Patterns, Speed Limits & Timing
8 Chapter 8: Subsonic Aerodynamics & Jet Aircraft Performance
8.1 Subsonic Jet Aerodynamics: Lift, Drag & Flight Regimes 8.2 High-Altitude Flight: Mach Number, Buffet & Coffin Corner 8.3 Transport Turbine Engines: Thrust, Specific Fuel & Bleed Air
9 Chapter 9: Transport Category Takeoff & Landing Runway Analysis
9.1 Takeoff Performance Speeds & Balanced Field Concept 9.2 Takeoff Climb Segments & Obstacle Clearance Gradients 9.3 Landing Performance: Field Lengths, 60% Rule & Contamination
10 Chapter 10: En Route Performance, Driftdown Profiles & ETOPS Operations
10.1 One/Two-Engine-Inoperative En Route Net Profiles & Driftdown 10.2 Extended-Range Operations (ETOPS): Philosophy & Regulations 10.3 ETOPS En Route Alternates: Adequate vs. Suitable & Critical Fuel
11 Chapter 11: Aircraft Weight & Balance, Center of Gravity, and Loading
11.1 Transport Aircraft Structural Weight Limits: Definitions & Rules 11.2 Center of Gravity Computations: Datum, Arm, Moment & Index 11.3 Mean Aerodynamic Chord (%MAC) Computations & Stability 11.4 Payload-Range Analysis, Zero Fuel Weight Tradeoffs & Loading
12 Chapter 12: Destination Alternate Airport Selection & Weather Rules
12.1 Destination Alternate Selection: 91.169 & Part 121 1-2-3 Rule 12.2 Flag & Supplemental Operations Destination Alternate Rules 12.3 Derived Alternate Minimums: 1-Nav and 2-Nav Facility Rules
13 Chapter 13: Part 121 Fuel Planning, Reserves & En Route Re-Release
13.1 Part 121 Domestic Fuel Requirements: Reserves & Calculations 13.2 Part 121 Flag Fuel Requirements: 10% Reserve & Island Rules 13.3 Supplemental Fuel Requirements & Holding Fuel Management 13.4 Redispatch and En Route Re-release Procedures
14 Chapter 14: Transport Systems, Pressurization & MEL/CDL Procedures
14.1 Transport Jet Auxiliary Power, Electrical, Hydraulic & Pneumatic Systems 14.2 Cabin Pressurization, Rapid Decompression & Oxygen Requirements 14.3 Master Minimum Equipment List (MMEL), MEL & CDL Procedures 14.4 Flight Controls, Autoflight, Fuel, Oil, Brakes, and Fire Protection
15 Chapter 15: Hazardous Materials, Duty Regulations & Emergency Procedures
15.1 Dangerous Goods Carriage by Air (49 CFR Part 175) & NOTOC 15.2 Dispatcher Duty Limitations, Rest Requirements & Fatigue 15.3 Emergency Authority, Declaration & Diversion Decision-Making 15.4 NTSB Part 830 Accident Reporting & Wreckage Preservation 15.5 Security, Overdue Aircraft, and FAA Emergency Services
16 Chapter 16: Communications, ATC, and Flight Plan Procedures
16.1 Voice, Data Link, Position Reports, and Lost Communications 16.2 ATC Facilities, Separation, ICAO Flight Plans, and Traffic Management
17 Chapter 17: Human Factors and Practical Dispatch Applications
17.1 Dispatch Resource Management, Human Error, and Risk Decisions 17.2 Manual Flight Planning, PIC Briefing, Flight Watch, and Postflight Closeout
2.4 Earth Motion, Regional Weather, Local Winds, and Water Phase Changes
Key Takeaways Explain This Topic AI
Coriolis deflects motion right in the Northern Hemisphere and left in the Southern Hemisphere.
Seasons mainly reflect axial tilt and changing solar angle/daylight, not distance from the Sun.
Sea/land breezes, slope winds, and valley cold pools can change airport conditions independently of a regional air-mass label.
Evaporation absorbs energy; condensation and freezing release energy.
Last updated: October 2026
Connect Global Weather to Local Operations
Appendix A requires the Earth's motion, regional and local weather, atmospheric wind patterns, and changes of state. These topics explain why a forecast can vary sharply between a coast, mountain valley, island, and inland plain. A dispatcher uses the physical setting to interpret observations and forecasts, rather than predicting every airport's weather from a single air-mass label.
Rotation, seasons, and unequal heating
The Earth rotates, creating the day/night heating cycle and the Coriolis effect in a rotating reference frame. Earth's axial tilt and orbit create seasonal differences in sun angle and daylight duration. Seasons are not primarily caused by the Earth being closer to the Sun in summer. Unequal heating changes pressure distribution, atmospheric circulation, and the timing of local convection and fog.
The pressure-gradient force accelerates air from higher toward lower pressure. Coriolis deflects motion to the right in the Northern Hemisphere and left in the Southern Hemisphere ; it changes direction rather than acting as a source of wind speed. Surface friction slows wind and permits flow across isobars toward lower pressure. Aloft, winds are more nearly parallel to pressure-height contours when forces are approximately balanced, with curvature and acceleration producing additional differences.
Global circulation and regional types
The simplified three-cell circulation model describes tropical Hadley, midlatitude Ferrel, and polar circulation. Trade winds, prevailing midlatitude westerlies, and polar easterlies are useful broad patterns. They are not fixed winds at every flight level or airport. Jet streams, fronts, terrain, and daily weather systems modify the local result.
Maritime environments supply moisture from oceans; continental environments can have larger temperature ranges and less moisture. Polar and tropical describe thermal/source-region characteristics. A maritime tropical air mass moving over a cold surface can become stable and foggy, while cold continental air crossing warmer water can become unstable and produce showers or snow. Track how the surface modifies the air, not just where the air originated.
Coastal and island circulations
In fair conditions, land often warms faster than water during daylight. A sea breeze can bring cooler air inland, changing runway winds and creating convergence that supports afternoon showers. At night, faster land cooling can support a weaker land breeze . Synoptic winds and cloud cover can suppress, displace, or alter these local patterns; a sea-breeze forecast is not a guarantee of a particular runway direction.
Islands combine marine moisture, sea/land-breeze boundaries, terrain, and prevailing trade winds. Windward slopes can be cloudier and wetter than nearby leeward terrain. A destination and an alternate on the same small island may share a tropical rainband or wind hazard, so geographical closeness does not automatically provide independent weather protection. Evaluate forecast winds and terrain/approach exposure at each airport.
Mountain and valley weather
Upslope flow cools through expansion and can form cloud, precipitation, and icing on windward terrain. Descending leeward air can warm and dry, producing a rain shadow or foehn/Chinook conditions. Strong flow across a stable mountain environment can also support waves and rotors. The lack of a visible cloud does not eliminate the hazard.
Daytime heating can create valley breezes and upslope motion. Nighttime cooling can create mountain breezes or drainage winds carrying cold dense air down slopes and into valleys. Pooled cold air supports inversions and fog while nearby higher terrain remains clear. During winter operations, combine these local effects with cold-temperature altitude correction, runway condition, and available approach/weather reporting information.
Plains and dry environments
Broad plains expose fronts and thunderstorm outflows with relatively little terrain obstruction. Moisture convergence, drylines, and low-level jets can support strong convection. Dry inland surfaces can heat rapidly and produce high density altitude, thermal turbulence, blowing dust, and dry microbursts when precipitation evaporates below high-based storms.
A high surface temperature is therefore relevant to both performance and weather. It can lower allowable takeoff weight while also contributing to convective potential. Forecast the actual combination of moisture, instability, and lifting rather than assuming heat alone guarantees a thunderstorm. Strong surface wind may be an outflow or pressure-gradient event without any storm directly over the airport.
Water changes of state and latent heat
- Process Change Heat relationship
- Evaporation Liquid to vapor Absorbs energy
- Condensation Vapor to liquid Releases energy
- Freezing / melting Liquid to solid / solid to liquid Releases / absorbs energy
- Sublimation Solid directly to vapor Absorbs energy
- Deposition Vapor directly to solid Releases energy
Evaporation cools air, supporting a precipitation-cooled downdraft or microburst. Condensation releases latent heat and modifies a saturated parcel's cooling rate. Supercooled liquid can remain liquid below freezing and then freeze on an aircraft. Frost can form by deposition when a surface is sufficiently cold; surface contamination must be addressed under the approved ground-icing program rather than assumed harmless because no rain occurred.
Wind-component exercise
For a hypothetical runway wind 20 knots at a 60-degree angle to the runway, the headwind component is 20 × cos(60°) = 10 knots , and crosswind is 20 × sin(60°) ≈ 17.3 knots . These are vector components, not separate winds to be added back as 27.3 knots. Apply the correct wind reference, gust treatment, and approved aircraft/operation limits before using them for performance.
In a coastal-afternoon scenario, the sea breeze shifts that crosswind while nearby convection produces gusts. Recheck runway suitability, takeoff/landing data, and alternate wind limits. The operational purpose of weather theory is a revised decision using current observations and approved performance, not a claim that the sea breeze or cloud type by itself dictates one universal outcome.
Official References
Source check: 2026-10-12 . 2026 FAA Aviation Weather Handbook ; Altimeter settings § 91.121 . For operational use, apply current issued authorizations and the assigned aircraft’s approved data.