1
Q
What four gases make up 99.98% of the atmosphere?
A
Nitrogen
Oxygen
Argon
Carbon Dioxide
2
Q
What are the five closest layers of Earth’s atmosphere?
A
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere
3
Q
Where does most weather occur?
A
Troposhere
4
Q
How high does the Troposhere extend?
A
Surface to 36,000’ high
As the gases decrease with height, the air becomes thinner, and temperature also decreases with height.
5
Q
How high does the stratosphere extend?
A
tropopause up to 31 miles above the Earth’s surface.
This layer hold 19% of the atmosphere’s gases, but very little water.
Temperature increases with height due to the absorption of UV radiation.
Note: commercial aircraft often cruise in the lower stratosphere to avoid atmosphere turbulence and convection in the tropopause.
Disadvantages of flying in this layer are increased fuel consumption due to warmer temperatures, increased radiation, and increased ozone concentrations.
6
Q
How high does the mesosphere extend?
A
From the stratopause to about 53 miles above the Earth.
Gases continue to thin so warming becomes less pronounced leading to a decrease in temperature with height.
7
Q
How high does the thermosphere extend?
A
From teh mesopause to 430 miles above the Earth. This layer is known as the upper atmosphere.
The gases become increasingly thin compared to the mesosphere and only high energy UV and X-ray radiation from the sun is absorbed.
Temperature increases with height and can reach 2,000 degrees Celsius near the top of the layer.
8
Q
How high does the Exosphere extend?
A
From the thermopause to 6,200 miles. In this layer, atoms and molecules escape into space, and satellites orbit the Earth.
9
Q
What is standard atmosphere?
A
15 degrees Celsius
29.92 Hg
1013.2 millibars
10
Q
What is wind?
A
Air in motion relative to the Earth’s surface.
11
Q
What are the three forces that affect wind?
A
Pressure Gradient Force
Coriolis Force
Friction
12
Q
What is Pressure Gradient Force?
A
Wind flows from areas of high to low pressure. These differences form the PGF.
Whenever a pressure difference develops over an area, the PGF makes the wind blow in an attempt to equalize the differences.
13
Q
In what direction does PGF flow?
A
High to low pressure and perpendicular to contour/isobars.
14
Q
What does closely spaced Isobars suggest?
A
Strong wind
15
Q
What is Coriolis force?
A
Rotation of the Earth causing air masses to shift their movement.
Note: If one views the moving mass from a rotating platform the path would look straight.
Air is deflected to the right in the northern hemisphere and left in the souther.
16
Q
Is Coriolis Force directly proportional to wind speed?
A
Yes
If wind speed doubles, Coriolis doubles.
Note: Coriolis varies with latitude. Zero at the equator and maximum at each pole.
17
Q
How does friction impact wind?
A
Friction between the wind and the terrain surface slows the wind.
The rougher the terrain, the greater the frictional effect.
The stronger the wind speed the greater the frictional effect.
18
Q
Above the frictional layer what two forces affect wind?
A
Coriolis Force and Pressure Gradient Force
19
Q
Wind Shear, what is it?
A
A sudden, drastic change in wind speed and/or direction over a very small area.
20
Q
Where can wind shear happen?
A
At any altitude
21
Q
What is the most dangerous type of wind shear?
A
low level wind shear.
22
Q
Where should you be most alert for wind shear?
A
thunderstorms and frontal systems
23
Q
What are Mountain Waves
A
The eddying of atmospheric currents around mountains.
24
Q
What does the atmosphere do when it encounters mountainous terrain?
A
-If the wind is weak or exceptionally dense, the mountain may act as a dam, stopping the air.
-Strong winds flow over/around mountains and cause waves to form.
-Strong winds plus an unstable atmosphere may result in a thunderstorm forming.
25
What’s the hazard to Mountain Waves?
produces strong down drafts and/or turbulence on the immediate leeward side of the mountain.
26
What are some visual indicators of Mountain Waves?
Lenticular Clouds and Rotor Clouds
-Sharp edged, lens shaped lenticular clouds.
-Cap clouds, Cirrocumulus Standing Lenticular, Altocumulus Standing Lenticular, Rotor Clouds
27
What is the definition of temperature?
The average kinetic energy of the molecules in matter.
Temperature is an indicator of the internal energy of the air.
28
What are three way heat is transferred into and through our atmosphere?
Radiation
Conduction
Convection
29
What is radiation with regards to heat transfer?
Heat coming off of an object.
Ex. Sitting near a fireplace. You aren’t touching the fire but the heat coming off the fire from the side is radiant heat.
30
What is conduction with regards to heat transfer?
Transfer of energy by molecular activity from one substance to another in contact.
Heat always flows from a warmer substance to the colder substance.
31
What is convection with regards to heat transfer?
the transport of heat within a fluid via motions of the fluid itself.
Ex. Water boiling in a pot.
Because air is a poor thermal conductor, convection plays a vital role in Earth’s atmospheric heat transfer process.
32
True or false: water is much more resistant to temperature change than land.
True
33
What is the temperature change with altitude?
2 degrees Celsius per 1,000’
34
What is a temperature inversion?
A layer in which the temperature increases with altitude.
Typically occurs over land on clear night with light wind.
-ground radiates faster than the overlying air. Air in contact with he ground cools, while air a few hundred feet stays the same.
35
If a temperature inversion exists on the surface what is it called? What if it is not on the surface?
Surface = Ground based inversion
Not on the surface = Inversion aloft
36
What is the principle characteristic of a temperature inversion?
stability and lack of turbulence.
37
What are the different types of precipitation?
Rain
Snow
Ice pellets
Freezing rain
38
What is an air mass?
A large body of air with generally uniform temperature and humidity.
39
What is the area an air mass originates called?
Source region
40
How are air masses classified?
Classified according to temperature and moisture properties of the source region.
Temp properties:
-Arctic: extremely deep cold air mass; develops mostly in winter over arctic ice/snow.
-Polar: a relatively shallow cool to cold air mass which develops over high latitudes.
-Tropical: a warm to hot air mass which develops over low latitudes.
Moisture properties:
-Continental: a dry air mass which develops over land
-Maritime: a moist air mass which develops over water.
41
What are the different types of air masses?
-Continental Arctic: Cold, Dry
-Continental Polar: Cold, Dry
-Continental Tropical: Hot, Dry
-Maritime Polar: Cool, Moist
-Maritime Tropical: Warm, Moist
-Maritime Arctic: Cold, Moist (rarely if ever forms)
42
What is a Front?
a boundary or transition zone between two air masses.
43
How is a cold front shaped and how does it move?
Cold fronts have a steep slope, and the warm air is forced up abruptly.
If the warm rising air is unstable this often leads to a narrow band of showers and thunderstorms along, or just ahead of the front.
44
How is a Warm Front shaped and how does it move?
Warm fronts have a gentle slope, so the warm air rising along the frontal surface is gradual.
This favors the development of widespread layered or strati form cloudiness and precipitation along, and ahead of, the front if the warm rising air is stable.
45
What are Occluded Fronts?
An Occluded Front emerges from the convergence of a cold front with a warm front.
Cold fronts typically move faster than warm fronts, so in time they catch-up to warm fronts.
46
What are sources of vertical motion in the atmosphere?
Orographic lift
Frontal lift
Buoyancy
47
How does air move in a High Pressure system?
clockwise and outward
“Down and out in the blues”
48
How does air move in a Low Pressure system?
Counterclockwise and inward
49
How does frontal lift work?
Cold, denser air wedges under warm, less dense air, forcing it upward.
Warm air rides up and over cold air in a process called over running.
50
What makes air buoyant?
Air near the ground can warm at different rates. Temperature differences result in different air densities, allowing warm air to rise and cold to sink.
51
What are some different cloud forms?
-Cirri form
-Nimbo form
-Cumuli form
-Strati form
52
What are the the different cloud levels?
High
Middle
Low
Extensive Vertical Development
53
What causes turbulence?
convective currents, obstructions in the wind flow, and wind shear.
54
What are the different types of turbulence?
Convective turbulence
Mechanical turbulence
Wind Shear turbulence
Clear Air Turbulence
Convective turbulence: turbulent vertical motions that result from convective currents and the subsequent rising and sinking of air. For every rising current, there is a compensating downward current.
Mechanical Turbulence: caused by obstructions to the wind flow, such as trees, buildings, mountains, and so on. A pilot has little or not indication of their presence.
Wind Shear Turbulence: The rate of change in wind direction and/or speed per unit distance and may be associated with either a wind shift or a wind speed gradient at any level in the atmosphere.
55
What are the ingredients necessary for a thunderstorm to form?
Sufficient water vapor
Unstable air
Lifting mechanism
Sufficient water vapor: commonly measured using dew point, must be present to produce unstable air.
Unstable air: virtually all showers/thunderstorms form in an air mass that is classified as conditionally unstable.
Lifting Mechanism: A conditionally unstable air mass requires a lifting mechanism strong enough to release the instability.
56
What is the life cycle of a thunderstorm?
Cumulus stage
Mature
Dissipating
Cumulus stage: a strong convective updraft. The updraft is a bubble of warm, rising air concentrated near the top of the cloud which leaves a cloudy trail in its wake.
Mature: the cell transitions to the mature stage when precipitation reaches the surface. Precipitation descends through the cloud and drags adjacent air downward, creating a strong downdraft alongside the updraft. The downdraft spread out along the surface as a mass of cool, gusty air.
Dissipating: The dissipating stage is marked by a strong downdraft embedded within the area of precipitation. Subsiding air replaces the updraft throughout the cloud, effectively cutting off the supply of moisture provided by the updraft. Precipitation tapers off and ends. The convective cloud gradually vaporizes from below.
57
What are the different kinds of thunderstorms?
Single cell
Multi cell
Supercell
58
What are the hazards of a thunderstorm?
Lighting
Strong wind
Downburst
Turbulence
Icing
Hail
Rapid altimeter changes
Static electricity
Tornado
59
What is a microburst?
the most severe form of wind shear
60
What are the general characteristics of a microburst?
-horizontal diameter of 1-2 miles
-depth of 1,000’
-lifespan of 5-15 minutes
-downdrafts of up to 6,000’ per minute
-headwind losses of 30-90 knots
-strong turbulence
61
what are some visual indicators of a microburst?
intense rain shaft at the surface, but virga at the cloud base.
Ring of blowing dust
62
How far away from a thunderstorm should you operate?
20 NM
63
What is frost?
the moisture in the air condensing and depositing itself on the ground (dew) and then freezing = frost.
Note: an aircraft must be clear of frost before operating.
64
What are the different types of icing?
Rime
Clear
Mixed
65
What is rime icing?
rough, milky, and opaque ice formed by the instantaneous freezing of small, super cooled water droplets after they strike the aircraft.
Rime icing formation favors colder temperatures, lower liquid water content and small droplets. It grows when droplets rapidly freeze upon striking the aircraft. The rapid freezing traps air and forms a porous, brittle, opaque, and milky colored ice.
66
What is Clear icing?
A glossy, clear, or translucent ice formed by relatively slow freezing of large, super cooled water droplets.
Clear icing conditions exist more often in an environment with warmer temperatures, higher liquid water contents, and larger droplets.
Clear ice forms when only a small portion of the drop freezes immediately while the remaining unfrozen portion flows or smears over the aircraft surface and gradually freezes.
67
True or false: clear ice is more hazardous than rime ice?
True
-it tends to disrupt airflow considerably more than rime icing.
-it is clear and more difficult to see and therefore can be difficult to recognize.
-it is difficult to remove since it can spread beyond the deice/anti-ice capabilities
68
What is Mixed Icing?
A mixture of clear and rime ice.
69
What are the hazards of icing?
It destroyed the smooth flow of air over the wing, increasing drag while decreasing the ability to create lift.
-As power is added to compensate for the additional drag, and the nose is lifted to maintain altitude, the angle of attack is increased allowing the underside of the wings and fuselage to accumulate additional ice.
The actual weight of ice on an aircraft is insignificant when compared to the airflow disruption it causes.
70
What is the percentage of lift lost and what is the percentage of drag gained when an ice layer of just the thickness of sandpaper forms?
30% loss of lift
40% additional drag
Note: larger accretions can make those numbers climb to 80% or more.
71
What is fog?
A visible aggregate of minute water droplets that are based at the surface and reduce visibility to less than 5/8 statute mile.
Note: the only difference between a cloud and fog is that, fog is on the surface.
72
What are the different types of fog?
-Radiation fog
-Mountain/Valley fog
-Advection fog
-Upslope fog
-Frontal fog
-Steam fog
-Freezing fog
-Mist
73
Radiation fog info dump
Terrestrial radiation cools the ground, the ground cools the air and when the air reaches its dew point, fog forms.
Note: generally a nighttime occurrence and often does not dissipate until after sunrise.
74
Mountain/Valley fog info dump
Ground cools overnight and the denser, cooler mountaintop air sinks into valleys and collects there.
Through the night the valley fills from the bottom with cold layers of air.
-cooler air lowers surrounding temperatures to the dew point.
-if there is sufficient moisture, fog forms in the valleys.
Note: most common in the fall and spring.
75
Advection fog info dump
Moist air moves over a colder surface cooling the air to below its dew point. Most common around coastal areas, but often moves deep into continental areas.
Deepens as wind speed increases up to 15 knots; winds much stronger than 15 knots lifts the fog into a layer of low stratus or stratocumulus clouds.
Note: west coast of the US is vulnerable to advection fog which frequently forms offshore because of cold water and then is carried inland by the wind.
*can remain for weeks, moving over land at night and retreating over water in the morning.
76
Upslope fog info dump
Forms as a result of moist, stable air being a diabetic ally cooled to or below its dew point as it moves up sloping terrain.
Wind speeds of 5-15 knots are most favorable; stronger winds tend to lift the fog into a low layer of stratus clouds.
77
Frontal fog info dump
When warm, moist air is lifted over a front, clouds, and precipitation may form.
If the cold air below is near its dew point, evaporation may saturate the cold air and form fog. The result is a continuous zone of condensed water droplets from the ground through the clouds.
Note: mostly associated with warm fronts.
78
Steam fog info dump
When very cold air moves across relatively warm water, enough moisture may evaporate from the water surface to produce saturation. As the rising water vapor meets the cold air, it immediately recondenses and rises with the air being warmed from below. Because the air is destabilized, fog appears as rising streamers that resemble steam.
79
Freezing fog info dump
Tiny, supercooled liquid water droplets in fog freeze instantly on exposed surfaces when temperatures are at or below freezing.
80
What is Haze?
suspension in the air of extremely small particles individually invisible to the eye, but numerous enough to give the air an opalescent appearance.
Occurs in stable air and is usually only a few thousand feet thick, but may extend to up to 15,000’
81
What is smoke?
suspension of small particles individually invisible the air produced by fires.
82
What is ash composed of?
silica
83
What are some obstructions to visibility or other hazards?
Haze
Smoke
Volcanic Ash
Blowing Snow
Dust Storms
Sand Storms
Haboob
84
What is the preflight requirements FAR?
91.103
85
What are some sources for weather?
AWC
1-800WX brief
Foreflight
FSS-inflight weather brief
Satellite weather
FIS-B
86
What Is a METAR?
Meteorological Aerodrome Report.
It is an observation of current surface weather reported in a standard international format.
87
What information and in what sequence does a METAR report?
1.Type of report
2.Station identifier
3.Date and time of report
4.Modifier
5.Wind
6.Visibility
7.Weather
8.Sky condition
9.Temperature/dewpoint
10.Altimeter setting
11.Remarks
88
What is a TAF?
Terminal Aerodrome Forecast.
A TAF is a report established for the 5 SM radius around an airport
89
How long is a TAF valid for?
24 to 30 hours
90
How often is a TAF updated?
4 times a day
91
How often are AIRMETs issued?
6 hours
92
What are the 3 types of AIRMETs?
SIERRA: denotes IFR and mountain obscuration.
Tango: Denotes turbulence, strong winds, and low level wind shear.
ZULU: Denotes icing and freezing levels.
93
What is a SIGMET?
In flight advisory concerning non-convective weather that is potentially hazardous to all aircraft.
Dust, sandstorms, severe icing, extreme turbulence, clear air turbulence not associated with thunderstorms, volcanic ash.
94
How long is a SIGMET valid for?
4 hours
6 hours (hurricane)
95
What is a convective SIGMET?
Weather advisory issued for hazardous convective weather that affects the safety of every flight.
96
What weather is a convective SIGMET issued for?
Severe thunderstorms with surface winds greater than 50 knots, hail at the surface 3/4 inches or greater
-Tornadoes
-Embedded thunderstorms
-Lines of thunderstorms
97
What is a PIREP?
A pilot generated report for weather.
98
What are the two types of PIREPs?
Urgent or Routine
99
Ultimately what is a weather brief and weather sources leading to?
A go/no go decision.
Note: at no point is this decision final. Cancel the flight at any time, even in the air.
Flight Notes
flashcards
Decks in class (17)
# Cards
-
POH50
-
Aviation Definitions28
-
Airspeeds15
-
Emergencies20
-
National Airspace System31
-
Aircraft Systems37
-
Human Factors60
-
Principles of Flight56
-
Performance and Limitations10
-
Navigation Systems and Radar Services49
-
Weather99
-
Instrument Mega Deck293
-
Basic Instrument Maneuvering41
-
Pilots Cafe107
-
Approaches28
-
Shepard Air (Instrument)547
-
Flight Insight Instrument CHECKRIDE Prep57
