Transcript How Types of Severe Weather Affect Aviation—Thunderstorms

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)
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
 When air rises, pressure
decreases, volume increases, and
temperature decreases
 When air descends the opposite is true
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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
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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
 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
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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
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Chapter 2, Lesson 3
Reproduced from US Department of
Transportation/Federal Aviation Administration
Mechanical Turbulence
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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
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Reproduced from NASA
Chapter 2, Lesson 3
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
Chapter 2, Lesson 3
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
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Chapter 2, Lesson 3
Reproduced from NOAA/Earth System Research
Laboratory
Thunderstorms—
Air Mass and Steady-State
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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
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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
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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
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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
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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
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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
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Chapter 2, Lesson 3
Courtesy of NOAA.
Activity 3: AtmosModeler
Lab—Temperature and Altitude
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Use the AtmosModeler interactive simulation
software to investigate how changes in
altitude affect temperature
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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
Chapter 2, Lesson 3
Activity 4: Severe Weather
Investigation
 Create
a presentation on one of the
severe weather events
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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
Chapter 2, Lesson 3
Next….
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Done – aviation
weather
Next – weather
forecasting
Chapter 2, Lesson 3
Courtesy of NASA/George Shelton