Meteorology Part 3 Flashcards
Icing defined
If the skin of the aircraft is below 0 degrees, ice will form.
Clear Ice
Rime Ice
Mixed Ice
Clear = slowly freeze after impact aircraft = covers more of the wing & smooth
Rime = immediate freeze, traps air, white & rough
Mixed = both
clear ice is usually from what cloud
cumuliform
Rime ice usually is formed from what cloud?
stratiform
Results of icing:
increase drag (300-500%)
increases weight
increase stall speed
decreases lift
decreases thrust
blocks vision
plugs pitot tube & static ports
catching rate
thin wing
large water droplets
high speed
icing conditions
0 to -25 = severe clear icing
-25 to -40 light to mod rime/mixed
below -40 = little chance of icing
if you notice ice…
turn around!
get to lower/warmer air
contact FSS for freezing level update
fast decisions!
air masses define
large sections of the troposphere with uniform properties
(can be thousands of miles)
Most common air masses in Canada (4 cold to warm)
1) Continental Arctic -dry, very cold, stable
2) Maritime Arctic -moist unstable in lower levels
3) Maritime Polar - moist, cool, unstable
4) Maritime Tropical - moist, hot, very unstable
3 factors that determine an air mass:
1) moisture
2) temperature
3) stability of air
cold air masses typically are:
instability
turbulence
good visibility
cumuliform cloud
percipitation: showers, hail, thunderstorms
warm air masses
stability
smooth air
poor visibility
stratiform cloud
precipitation: drizzle
fronts =
the boundary between 2 air masses
–typically air masses do not readily mix
frontal slope
the distance from the leading surface of the front to where it meets the ground.
Ratio
cold front ratio = 1/50 to 1/100miles
warm front ratio = 1/150 to 1/200miles
overrunning frontal slope
a faster moving warm front will overrun & lift over a cold air mass
undercutting frontal slope
faster moving cold mass will undercut the warm air and lift it up
cold fronts result =
fast cold air comes in and lifts warm air = warm air lifts, expands, cools and then condenses to form clouds & precipitation
warm front results
fast warm air overruns cold = warm lift is liften, expands, cools, condenses, and forms clouds/precipiation
There are front symbols (you need to know these)
1) warm front
2) cold front
3) stationary front
4) occluded front
1) red half circles
2) blue triangles
3) alternating red half circles & blur triangles
4) purple half circle/triangle alternating
frontogenesis & frontolysis
frontogenesis = front being created
frontolysis = front dissipates
Upper fronts
A non-occluded situation where an air mass is sitting on top of another air mass.
Ex: Rockey mnt. very cold air is trapped at the surface = warm front will ride over the colder air below.
Frontal depression
Disturbance created due to the instability of frontal situation (temp diff between air masses)
Occlusion or occluded front
aka: trowal
warm air is sandwiched between cold and cool air. Faster moving cold air will catch up with itself & undercut the warm air between the cooler air in front. = lift up this air & create an occlusion
Weather at a front depends on:
1) speed of front
2) moisture
3) stability of air being lifted
1) faster = more abrupt vertical motion = squall lines & severe weather can result.
2) Moisture = clouds = precipitation to form.
3) causes diff cloud types. more showery & turbulent.
3 things required to form a thunderstorm
1) Large instability
2) Lifting agent
3) High moisture content
–produced by cumulus clouds
Life-cycle of a thunderstorm
1) Cumulus Stage
–grows to become a towering cumulus cloud.
2) Mature Stage
–precipitation. Strong winds carry clouds ahead of storm = forms anvil shape.
3) Dissipating Stage
-~30mins after cells start to form. mainly downdrafts. least hazardous.
Clear air turbulence (CAT)
–higher altitudes
–rhythmic & more annoying than harmful
–usually associated with wind shear
SIGMETs Verse AIRMETs
both = info on hazardous weather conditions
SIGMET = more severe. aka: thunderstorms, dust storms, etc.
AIRMET = less severe. aka: turbulence, visibility, and icing
ATC is required to advice their pilots whenever a SIGMET is issued within 150 nm of their airspace.
just fyi if they are busy they might not give you details. you are responsible for that info from FSS
virga definition
precipitation that does not make it to the ground.
* avoid *
microburst define
a downdraft (sinking air) in a thunderstorm that is less than 2.5 miles in scale
ADF what is it & what can it help with?
Automatic direction finding (older planes often)
can help find lightning. Strikefinder or weather radar would be better tho.
