Meteorology for pilots

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Meteorology for pilots
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Principles Breakdown

• Basic Weather Theory
• Weather Patterns
• Weather Hazards

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• Any information paired with the FAA tag are
  informational statements from which FAA written
  tests are based from know them!!

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Basic Weather Theory

• The Atmosphere

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The Atmosphere

• Troposphere
• Tropopause
• Stratosphere
• Mesosphere
• Thermosphere

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Atmosphere
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Atmospheric Travel
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Three-Cell Circulation Pattern
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Three-Cell Circulation Pattern
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Atmospheric Pressure
Isobars Pressure gradients Trough area of
low Ridge-area of high High Low Col-neutral areas
Variations in altimeter settings between weather
reporting points are primarily caused by the
unequal heating of the earths surface.
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Coriolis Force
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Frictional Force
Friction causes wind to shift directions when
near the earths surface.
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Global Wind Patterns
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Local Wind Patterns
Convective circulation patterns associated with
sea breezes are caused by cool, dense air moving
inland form over the water.
Sea Breeze Land Breeze
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Local Wind Patterns

• Valley Breeze

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Local Wind Patterns

• Mountain Breeze

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Local Wind Patterns

• Katabatic WindsStronger then mountain breeze

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WEATHER PATTERNS
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Atmospheric Stability

• Stability-the atmospheres resistance to vertical
  motion.

Stability of an air mass is decreased by warming
from below.
Lapse rate the rate of change of temperature to
change in altitude. 2 C or 3.5 F per 1000 feet.
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Atmosphere Stability

• The actual lapse rate can be used to determine
  the stability of the atmosphere

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Temperature Inversions

• A smooth, stable layer of air and a temperature
  increase with altitude are features of a
  temperature inversion. Visibility in an
  inversion is usually poor due to trapped
  pollutants. In addition, high humidity beneath a
  low-level temperature inversion can contribute to
  the formation of fog, haze, or low clouds

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Temperature Inversions

• A surface-based temperature inversion is often
  produced by terrestrial radiation on clear, cool
  nights when the air is relatively calm.

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Change of State
Every physical process of weather is accompanied
by a heat exchange. AND Water vapor is added to
the atmosphere by evaporation and sublimation.
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Dewpoint
Dewpoint is the temperature to which air must be
cooled to become saturated.
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Dewpoint
The calculation of a cloud base
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Dew and Frost

• Frost forms when the temperature of the
  collection surface is at or below the dewpoint of
  the surrounding air and the dewpoint is below
  freezing.

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Clouds
Clouds, fog, or dew always form when water vapor
condenses.
A small and decreasing temperature/dewpoint
spread indicates conditions are favorable for the
formation of fog.
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Clouds Clouds Clouds
Types of Clouds Low Clouds Fog Middle
Clouds High Clouds Clouds with Vertical
Development
Clouds are grouped by families according to
their altitudes.
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Low Clouds (Suface-6,500 ft)

• Stratus

Stratus clouds form when moist, stable air flows
upslope.
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Low Clouds

• Stratocumulus

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Low Clouds
Nimbostratus
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Fog
Radiation Fog
Radiation fog forms in moist air over low, flat
areas on clear, calm nights.
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Fog
Advection Fog
Advection and upslope fog requires wind for
formation. Both types of fog commonly occur along
coastlines where sea breeze transport air from
warm water to the cooler land surfaces.
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Fog
Upslope Fog
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Fog
Steam Fog
Low-Level turbulence and aircraft icing are
associated with steam fog.
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Middle Clouds (6,500-20,00 ft)
Altocumulus Clouds
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Middle Clouds

• Altostratus

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High Clouds (20,000 ft)

• Cirrus

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High Clouds

• Cirrostratus Clouds

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High Clouds
Cirrocumulus
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Clouds with Vertical Development

• Cumulus Clouds

Vertical cloud development and turbulence result
from the lifting of unstable air
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Clouds with Vertical Development
Towering Cumulus
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Clouds with Vertical Development

• Cumulonimbus Clouds

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Precipitation
Virga
Ice pellets at the surface are an indication of
a temperature inversion and freezing rain at a
higher altitude.
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Airmasses

• A large body of air with fairly uniform
  temperature and moisture content.

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Airmasses
Stable air is generally smooth with layered or
stratiform clouds. Visibility is usually
restricted, with widespread areas of clouds and
steady rain or drizzle.
Moist unstable air causes the formation of
cumuliform clouds, showers, turbulence, and good
surface visibility.
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Fronts

• Fronts are boundaries between airmasses

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Fronts

• One of the most easily recognized
  discontinuities across a front is the change in
  temperature

When you are flying across a front, you will
notice a change in wind direction. Wind speed
may also change.
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Cold Fronts and Warm Fronts
Cold Front Warm Front
Steady precipitation with little turbulence
usually precedes a warm front.
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WEATHER HAZARDS
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Thunderstorms

• Thunderstorm formation requires unstable
  conditions, a lifting force, and a high moisture
  levels.

Cumulus Stage
Mature Stage
Dissipating stage
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Life Cycle

• The cumulus stage is characterized by continuous
  updrafts.
• Thunderstorms reach the greatest intensity
  during the mature stage which is signaled by the
  beginning of precipitation.
• A dissipating thunderstorm is characterized by
  downdrafts.

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Thunderstorm Hazards
Lt. Col. William H. Rankin, USMC
Severe turbulence often exists in a cumulonimbus
cloud, the most turbulent of all clouds.
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Lightning!
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Lightning
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Hail
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Why Hail Can be Bad
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Turbulence

• If you encounter turbulence in flight establish
  maneuvering speed and try to maintain a level
  flight attitude.

Low-Level Turbulence
Mechanical Turbulence
Convective Turbulence
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Wake Turbulence
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Why wake Turbulence is bad
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The FAA says
Wing tip vortices are created when an airplane
generates lift.
The greatest vortex strength occurs when the
generating aircraft is heavy ,slow, and in a
clean configuration.
Wingtip vortices tend to sink below the flight
path of the aircraft witch generated them. The
are most hazardous during light quartering
tailwind conditions.
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Load Factor

• The load factor imposed on an airplane will
  increase as the angle of bank is increased
• Increasing the load factor will cause an
  airplane to stall at a higher speed.
• Why? Think T-Bird

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What can you do to avoid death?
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Mountain Wave Turbulence
Mountain wave turbulence can be anticipated when
the winds across a ridge are 40 knots or more,
and the air is stable.
The crest of mountain waves may be marked by
lens-shaped, or lenticular clouds.
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Wind Shear!

• Wind shear often exists near the surface when
  there is a frontal system, thunderstorm, or
  temperature inversion with strong upper-level
  winds in the area. Wind shear is also associated
  with clear air turbulence.

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But wait.

• Wind shear may also occur during a low-level
  temperature inversion when cold, still surface
  air is covered by warmer air which contains winds
  of 25 knots or more at 2,000 to 4,000 feet above
  the surface.

WIND SHEAR CAN EXIST AT ANY ALTITUDE AND MAY
OCCUR IN ALL DIRECTIONS.
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Icing
Visible moisture is necessary for structural
icing to form. Freezing rain usually produces
the highest rate of ice accumulation.
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Le Fin
Thank you come again.