1. Explain the weather hazards associated with
aviation.
2. List the tyes of severe weather that affect
aviation.
3. Describe arctic and tropic weather
characteristics.
1. Weather Hazards
2. Severe Weather
3. Arctic and Tropic Weather
Weather Hazards
• Reduced Visibility
• Three miles lateral visibility is acceptable
for safe flight under visual flight rules
(VFR).
• Possibility for accidents is greatest when
visibility is reduced and the pilot is not
trained to fly according to instrument flight
rules (IFR).
• Clouds, rain, snow, fog, and obstructions.
• Haze and smoke can reduce visibility when
the wind is calm.
Weather Hazards
• Reduced Visibility
• Blowing dust, sand, and snow
• Whiteouts
Weather Hazards
• Icing
• Ice is present in the atmosphere at all
times-15,000 feet in summer and as low as
1,000 feet in winter.
• Glaze and Rime ice form on an airplane’s
windshield, its propeller, and other
aerodynamic surfaces.
• Glaze ice is formed and builds quickly as an
airplane flies through super-cooled rain
droplets.
Weather Hazards
• Icing
• Rime ice forms when an
airplane is flying through
super-cooled cloud
condensation.
• Frost disturbs airflow to
reduce lift efficiency.
• Larger, more sophisticated
aircraft are equipped to break
or melt ice as it is formed.
Severe Weather
Severe Weather
• The NWS severe weather classifications
are based upon destructive effects with
regard to surface cultural features.
Severe Weather
• Thunderstorms
• A storm accompanied by thunder and
lightning.
• A Thunderstorm is local in nature and is
always produced by the growth of a
cumulus cloud into a cumulonimbus cloud.
• Three stages
• Cumulus
• Mature
• Dissipating
Severe Weather
• Thunderstorms - Cumulus Stage
Severe Weather
• Thunderstorms - Mature Stage
Severe Weather
• Thunderstorms - Dissipating Stage
Severe Weather
• Tornadoes
• Local storm that focuses destructive forces
on a small area.
• Occurs with severe thunderstorms.
• When it touches the ground its path may
be very erratic.
Severe Weather
• Tornadoes
• Destructiveness is caused by high winds.
• Very low pressure gives tornadoes great
suction.
Severe Weather
• Tornadoes
• Occur most often in the spring months and
in the afternoon hours.
• Very difficult to forecast.
Severe Weather
• Hurricanes
• A strong tropical cyclone with winds that surpass
100 mph.
• A large revolving storm with a calm center (eye).
Severe Weather
• Hail
• May be within a strong cumulus cloud
before any type of precipitation falls to the
surface.
• The combined velocity of an aircraft and
hail gives these small pellets a tremendous
amount of energy.
• If the pellets are “hard” because of
exceptionally cold temperatures at their
level, aircraft will experience damage.
Hail
Orlando, Florida…1992
Severe Weather
• Hail
• Encounters with larger hail are even more
damaging. Hail having the size, weight,
(baseball size), and velocities produced by
thunderstorms in the western and
mountain areas could rip a small plane
apart.
• Hail and rain pulled into an aircraft engine
can cause the engines to stall and flame
out, as well as cause internal damage.
Arctic and Tropic Weather
• Arctic Weather
• Mountains around Arctic Circle holds in cold
air
• Precipitation is light
• Strong winds occur in fall and winter
• Visibility is a major problem
Arctic and Tropic Weather
• Tropic Weather-fronts are rare and there
is more moisture in the air, especially in
the oceanic and coastal regions.
• Oceanic Weather
• Clouds cover about half the sky over the tropical
oceans.
• Northeast and southeast trade winds converge.
• When the wind convergence gets strong,
thunderstorms develop that may produce winds up
to 70 mph.
Arctic and Tropic Weather
• Tropic Weather
• Island and Coastal Weather
• When approaching a coastal area or an island,
the aviator should be prepared for instrument
conditions.
• Precipitation and cloudiness are heavier on
windward side.
• One of the major factors influencing tropical
weather is the easterly wave.
• As the wave line approaches, the pressure falls
and the wind shifts to the east as the line
passes.