Aviation Weather

Warm-Up Questions CPS Questions 1-2 Chapter 2, Lesson 3

Lesson Overview  Causes of atmospheric instability  Types and causes of turbulence  How types of severe weather affect aviation Chapter 2, Lesson 3

Quick Write Colonel Duckworth was an expert in instrument flying. Why was this skill important when flying through a hurricane? (Note to teacher: Use “Pick a Student” button in CPS) (Note to teacher: Use “Pick a Student” button in CPS) Chapter 2, Lesson 3 Courtesy of the National Museum of the USAF

Causes of Atmospheric Instability  Small vertical movements grow until they produce turbulent airflow and air circulation  Adiabatic process takes place in upward and downward moving air upward and downward moving air  When air rises, pressure decreases, volume increases, and decreases, volume increases, and temperature decreases temperature decreases  When air descends the opposite is true Chapter 2, Lesson 3 Reproduced from NOAA/National Weather Service

Causes of Atmospheric Instability, cont.  Water vapor is less dense than air  Moisture decreases air density, causes air to rise  Decrease in moisture makes air denser and causes it to sink  Moist air cools at a slower rate than dry air  Combination of moisture and temperature determines air stability and weather Chapter 2, Lesson 3

Activity 1: Air Lapse Rates  Convert Celsius temperatures to Fahrenheit temperatures  Review the examples and then complete the temperature conversion problems Chapter 2, Lesson 3

Learning Check Questions CPS Questions 3-4 Chapter 2, Lesson 3

Thermal Turbulence  Rise of warm air, taking place on a local scale  Plowed ground, rocks, sand, and barren land emit a large amount of heat of heat  Water, trees, and other growing things absorb heat  These reactions to sun’s energy results in uneven heating of the air, creates small areas called convective currents Chapter 2, Lesson 3 Reproduced from NOAA/Earth System Research Laboratory

Convective Currents  Create bumpy, turbulent air  On low-altitude flight, pilots may run into updrafts over pavement or barren places, and downdrafts over water or forests  To avoid these turbulent conditions, they can fly at higher altitude, even above cumulus clouds Chapter 2, Lesson 3 Reproduced from US Department of Transportation/Federal Aviation Administration

Mechanical Turbulence  Generated by resistance of one object moving over another  As air moves over Earth’s surface, friction that develops between air and surface modifies the air’s movement  Large objects—mountains to man-made structures such as buildings—generate mechanical turbulence Chapter 2, Lesson 3 Reproduced from US Department of Transportation/Federal Aviation Administration

Wind Shear  Abrupt, dramatic change in wind speed, direction, or both  Low-level are linked with thunderstorms, and temperature inversions, with strong upper-level winds  High-Level begins around 18,000 feet and can produce clear air turbulence Chapter 2, Lesson 3 Reproduced from NASA

Activity 2: Types of Turbulence   Describe the type of turbulence presented and explain its impact on flight using the illustrations provided Chapter 2, Lesson 3

Learning Check Questions CPS Questions 5-6

How Types of Severe Weather Affect Aviation—Thunderstorms  Convection triggers thunderstorms  Water vapors rising with warm air condense into clouds  Convection process then continues within the clouds  At the tropopause the unstable atmosphere stabilizes Chapter 2, Lesson 3 Reproduced from NOAA/Earth System Research Laboratory

Thunderstorms— Air Mass and Steady-State  Air mass occur in unstable air, last only an hour or two  Warm surface temperatures cause this type of storm  Steady-state often form into narrow band of active thunderstorms called squall lines  Updrafts grow stronger and last much longer than in an air mass storm Chapter 2, Lesson 3 Reproduced from US Department of Transportation/Federal Aviation Administration

Hazardous Flying Conditions  Look for squall lines, tornadoes, turbulence, icing, hail, lightning, and poor visibility  Light aircraft won’t be able to fly over thunderstorms  Air Force instructs pilots to fly 20 miles from the storm’s edge Chapter 2, Lesson 3 Courtesy of NOAA Photo Library; OAR/ERL/NSSL

Squall Lines  Develop in moist, unstable air, on or in advance of a cold front  Often contain steady-state thunderstorms  Form quickly, are strongest in the late afternoon and early evening Chapter 2, Lesson 3 Courtesy of NOAA/National Weather Service

Tornadoes  Materialize out of the most violent thunderstorms  Can sharpen into a powerful vortex that reaches from the ground into the clouds  Funnel-shaped cloud that stretches earthward from a cumulonimbus base Chapter 2, Lesson 3 Courtesy of NOAA/National Weather Service

Turbulence  Inside a cloud, pilots encounter the strongest turbulence  Outside of clouds, as much as several thousand feet above and 20 miles sideways  Gust front may stir up trouble as far as 15 miles ahead of any storm Chapter 2, Lesson 3 Courtesy of NOAA/National Weather Service.

Icing—Hail   Icing, is a product of updrafts   In a thunderstorm, the updraft lifts water vapor above freezing level,, the water supercools   Hail, another form of supercooled water   Can be just as dangerous to aircraft as turbulence Chapter 2, Lesson 3 Reproduced from US Department of Transportation/Federal Aviation Administration.

Lightning—Poor Visibility   Lightning—hazard that’s most closely associated with thunderstorms   Can puncture an aircraft’s skin, damage its communications and navigational equipment   Poor Visibility— generally visibility is near zero within a thunderstorm cloud Chapter 2, Lesson 3 Courtesy of NOAA.

Activity 3: AtmosModeler Lab—Temperature and Altitude  Use the AtmosModeler interactive simulation software to investigate how changes in altitude affect temperature  Gather and record data on temperature and altitude then use that information to make calculations Chapter 2, Lesson 3

Learning Check Questions CPS Questions 7-8

Activity 4: Severe Weather Investigation  Create a presentation on one of the severe weather events  Conduct and investigate research using the sources identified Chapter 2, Lesson 3

Summary  Causes of atmospheric instability  Types and causes of turbulence  How types of severe weather affect aviation

Chapter 2, Lesson 3 Review Questions CPS Questions 9-10

Next….  Done – aviation weather  Next – weather forecasting Chapter 2, Lesson 3 Courtesy of NASA/George Shelton