Part 1 of 3, most pilots loose the basics when they start flying due to numerous reasons. Whatever your reason, don't let not coming to this seminar be one of them. This three part series will fill in the memory gaps and show you how easy it can be to understand weather systems.
2. The basics of aviation weather, including the cases of
carious weather phenomena and how they can affect
the safety of flight.
For more information on aviation weather, refer to
Aviation Weather for Pilots(AC 00-6A)
Aviation Weather Services (AC 00-45G)
Internet Communications of Aviation Weather and
NOTAMS (00-62)
Introduction
6. Pressure Systems
Highs
H surrounded by L
Lows
L surrounded by H
Ridge
Elongated are of H
Trough
Elongated are of L
Col
Neutral area between 2 H or 2 L
Atmospheric Pressure
7. Wind
• Convection
• Pressure Gradient Force
• Corriolis Force
• Friction
• Global Circulation Patterns
• Jet Stream
8. Land & Sea Breezes
Sea Breeze
Land Breeze
Mountain/Valley Winds
Valley Winds
Mountain Winds
Katabatic Winds
Wind Shear
Local/Small Scale Winds
9. Moisture
• Water Vapor
– Relative Humidity
– Dewpoint
• Change in State
– Evaporation
– Condensation
– Freezing & Melting
– Sublimation & Deposition
10. Super-Cooled Water?
Exist at temps below freezing
Freeze upon impact with an exposed object
Condensation Nuclei
Microscopic particles
Serves as a place for condensation to form
Salt, dust, by-products of combustion
Moisture
11. Clouds/Cloud Formation
• Formation
– Air moving over a cold surface
– Air stagnating over a cold surface
– Expansion cooling of upward moving air
• Classification
– Fog
– Low Clouds
– Middle Clouds
– High Clouds
– Clouds with Extensive Vertical Development
12. Low Clouds
Almost entirely of water
Super cooled water, snow, ice
Surface to ±6,500’
Middle Clouds
Primarily of water
Most is Super cooled
Bases range from ±6,500’ to ±23,000’
Classification
13. Classification
• High Clouds
– Almost entirely ice crystals
– Base range 16,500 to FL450
• Clouds with Extensive Vertical
Development
– Super cooled water above the freezing level
– Tops may be ice crystals
– Base range from 1,000 to above 10K
14. Particle Growth
Via added condensation or sublimation
Via collision of particles
Precip vs. Cloud Thickness
To produce significant precip, 4000’ thick
Thicker the cloud, heavier the precip
Precipitation
17. Temperature Inversion
An increase in temperature
with an increase in altitude
Lapse rate is inverted
Usually confined to shallow
layers of air
Visibility is often restricted
19. Moistures Role in Stability
Unsaturated
• 3˚C/1000’
• Unstable
Normal
• 2˚C/1000’
• Stable
Saturated
• 1.1˚ to
2.8˚C/1000’
• Unstable
20. Every physical process of weather is
accompanied by or is the result of a
_____________.
1. Movement of air
2. Pressure differential
3. Heat exchange
0%
0%
0%
Countdown
20
21. What causes variations in
altimeter settings between
weather reporting points?
1. Unequal heating of the Earth’s
surface
2. Variation of terrain elevation
3. Coriolis force
0%
0%
0%
Countdown
20
22. The wind at 5,000 feet AGL is
southwesterly while the surface wind
is southerly. The difference is
direction is primarily due to?
1. Stronger pressure gradient at higher
altitudes
2. Friction between the wind & the
surface
3. Stronger Coriolis force at the surface
0%
0%
0%
Countdown
20
23. Convective circulation patterns
associated with sea breezes are
caused by?
1. Warm, dense air moving inland from
over the water
2. Water, absorbing & radiating heat
faster than the land
3. Cool, dense air moving inland from
over the water
0%
0%
0%
Countdown
20
24. The development of thermals
depends upon ___________.
1. A counterclockwise circulation of air
2. Temperature inversions
3. Solar heating
0%
0%
0%
Countdown
20
25. Air Masses
• What is an air mass?
– Large body of air with fairly uniform
• Temperature
• Moisture content
– Forms when air remains stationary and takes
on the characteristics of the underlying
surface
26. Temp & moisture content of the underlying surface
Tropical oceans & large deserts
Middle latitudes are poor regions
Source Regions
28. As it moves from its source region, it begins to
change
Warming from below can cause instability
Cooling from below may result in stability
May also cause poor visibility from fog and low clouds
Modification
30. Change in temp
May be abrupt or gradual
Change in wind direction or velocity
Always shifts to the right in the Northern Hemisphere
Change in pressure
Usually a drop as you approach it
Always reset your altimeter
Frontal Passage Detection
31. Cold Fronts
Hugs the
ground as it
moves due to
gravity
Forces
warmer less
dense air aloft
Movement is
usually in an
easterly
direction
33. Fast Moving Cold Fronts
Moved along by intense high pressure system
Surface friction causes a steep frontal slope
Wide difference between temp & moisture
between the two masses
Squall lines will precede if the air is moist and
unstable. Usually 50 to 300 miles ahead.
38. Occurs when two air masses are equally balanced
A mix of both air masses may be present for several
days
Stationary Fronts
39. Frontal Occlusions
• Occurs when a fast moving cold front
catches up to a slow moving warm front
• The difference in temperature determines
the front that is produced (warm or cold
front occlusion)
41. Thunderstorms
• 3 conditions necessary
– Unstable lapse rate
– High moisture content
– Some form of lifting action
42. 3 stages
Cumulus or building stage
Continuous updrafts
Mature stage
Rain at the surface
Dissipating stage
Downdrafts
Anvil top
Thunderstorms
43. Types of T-Storms
• Air Mass
– Convection on hot summer days
• Frontal
– Collision of 2 AM’s
• Orographic
– Mountainous areas
• Converging Air flow from 2 active storms
• Squall lines
45. Do’s & Don’ts
DO NOT
• Take off or land in the
face of a storm
• Fly under a storm
• Fly in a cloud mass
without airborne radar
• Trust the outward
appearance of a cloud
DO
• Avoid by 20 miles
• Clear the tops by 1000’
for each knot wind
• Circumnavigate the area
for 6/10th coverage
• Avoid lightning areas
• Regard tops of 35K or
higher as hazadous
46. Tighten your seatbelt & secure loose items
Plan & hold your course for minimum time through the
storm
Plan to enter below the freezing level
Pitot heat & carb heat on
Set power to establish Va
Turn up flight deck lighting
Turn off autopilot
If You Can’t Avoid
47. During Penetration
• DO keep you eyes on your instruments
• DO maintain maneuvering speed
• DO Allow the aircraft to “Ride the Waves”
• DO Maintain Course for a minimum time
through the storm
48. Can take place at any altitude
Can be caused by wind shear, convection currents, &
obstructions to airflow
Often found near the jet stream
CAT
55. Cooling from aloft tends to
make an air mass more…
1 2
50%50%
1. Stable
2. Unstable
Countdown
20
56. When an air mass is warmed from
below, its stability is…
1 2
50%50%
Countdown
20
1. Increased
2. Decreased
57. Transition zone between two
different air masses…
33%
33%
33%
1 2 3
1. Frontal zone
2. Trade wind
3. Trough
Countdown
20
58. This will always change when flying
across a front…
33%
33%
33%
Countdown
20
1. Wind Direction
2. Type of precipitation
3. Stability of the air mass
59. Cold fronts in the US generally
move to the…
1. East-Northeast
2. East-Southeast
3. West-Southwest
4. South
0%
0%
0%
0%
Countdown
20
60. What type of front generally produces
the most violent flying weather?
1. Warm
2. Cold
3. Fast-moving cold front
4. Stationary
0%
0%
0%
0%
Countdown
20
61. What type of cloud is associated
with fast-moving cold fronts?
1. Cirrus
2. Altostratus
3. Altocumulus
4. Cumulonimbus
0%
0%
0%
0%
Countdown
20