ATSC 113 EVALUATION QUESTIONS WITH ANSWERS
2025/2026
Forms from collision of small ice crystals & hailstones (graupels)
Small ice crystals (+) carried to the top of TS by updraft to anvil while larger graupel (-)
towards bot as they fall.
When the voltage dif. is big enough, insulative air ->ionized, conductive. Greater build
up of voltage = longer lightning
P-static - Sparks on the outside of aircraft from contact with uncharged particles and (-)
builds up on the surface.
(St. Elmo Fire = corona discharge as filaments of light writhing on the outside).
Cumuliform clouds - Warm humid air rising through cooler surrounding air. Strong
updrafts.
S - Cumulus humilis
M - Cumulus mediocris
L - Cumulus congestus
XL -Cumulonimbus/TS
Happens when air near ground is colder than the ground (clear day w/ sunshine).
Happens behind cold front. *btw updrafts are weaker downdrafts of clear air. downdraft
causing wind gusts leading to darker patches of water = "cat's paws"
Stratiform clouds - Warm air slides up along cold air. Seen ahead of warm front. Not
usually turbulent but may have supercooled liquid.
H - Cirrus, Cirrostratus, Cirrocumulus
M - Altostratus, Altocumulus
L - Stratus, Nimbostratus
It goes H - M - L (w/ light rain or snow) in sequence.
Stratus vs Nimbostratus - Nimbo (diffuse) precipitating while Stratus is not (well
defined).
Castellanus - Special cloud
Look like small castle turrets, sign of atm becoming unstable, TS possible later. Cloud
diameter similar to height.
A thin cold air layer above warm air -> warm air rises -> warm-cold-air sandwich ->
castlellanus, a type of stratiform cloud.
Convective circulations do not touch the ground, contained in warm-cold air sandwich.
Racist Joke - A black Jewish boy runs home from school one day and asks his father,
"Daddy, am I more Jewish or more black?" The dad replies, "Why do you want to know,
son?" "Because a kid at school is selling a bike for $50 and I want to know if I should
talk him down to $40 or just steal it!"
Yomama Joke - Yo mama so stupid, she sold her car for gas money.
,Billow (Kelvin Helmholz Waves) clouds - Indicative of wind shear & CAT, smooth air
often above or below.
Wind shear causes waves in a cooler layer under warmer air. Short wavelength, thin
waves.
Parallel bands of clouds form at each crest of waves only when rising cool air is humid.
Associated with unstable air along with castellanus.
Lenticular (Mt-wave) Cloud - Indicates vertical wind oscillation & possible Mt wave
turbulence. Wind hits Mt -> rises and comes back down, overshoots due to inertia ->
rises again.
In the upward portion, air cools -> cloud. When it descends, cloud evap. Clouds appear
stationary -> "standing lenticular". First wave over Mt = "Cap Cloud"
Rotor Clouds - Turbulent clouds that form under crest of Mt waves.
Rotate about a horizontal axis parallel to Mt range. Associated w/ strong turbulence &
violent up/down drafts. Change in wind direction over short distance makes flying
extremely dangerous.
Banner Clouds - Mt. special cloud along with lenticular & rotor clouds.
Forms on downwind side of Mt. Wind causes low P on the other side of the Mt peak,
sucking up lower alt air -> vapour condenses to clouds.
Pyrocumulus & Pileus - Pyrocumulus: forest fires & volcanoes, heat & moisture may
lead to TS.
Pileus: Form over fast-growing cumulus clouds, harmless, shore-lived til cumulus rises
through.
Fractus clouds - Low-alt, ragged cloud aka scud. Indicates high humidity and strong
wind at low alt. Forms when; (1) rain falls into cloud-free air -> evaporates ->
recondenses into cloud (if cloud touches ground = precipitation fog). (2) humid, cool air
near ground lifted up by turbulence to lifting condensation level -> clouds form.
Clouds formed by extra heat, updraft, turbulence - Pyrocumulus, Pileus, Fractus clouds
Man-made clouds - Fumulus - clouds over cooling towers.
Contrails - Aircraft condensation trails, formed from water vapor from jet engines, drawn
into wingtip vortices, indicate strong wake turbulence.
Cross Winds & Tail Winds & Head Winds - Tail winds are good for travel but bad for
take-off/landing.
Crosswinds can be compensated by crabbing but bad for take-off/landing.
Try to land/take-off on a runway w/ # closest to wind direction for a headwind (i.e. 14 =
135o).
, Wind shear - change of wind speed &/ direction w/ altitude. Stronger when near-surface
winds are faster. Wind shear near ground may make landing and take-off difficult. There
are strong vertical shear in warm (ahead) & cold fronts (behind).
Can be caused by weather system - synoptic scale/convective shear OR Mt winds - Mt
waves, wind channeling, downslope windstorm. OR turbulence behind obstacle OR
aircraft.
Gap Winds - TRapped cold air flowing at high speed through passes & gaps. Also
applies down narrow fjords or straits. Strongest when cold air trapped under a strong T
inversion.
Barrier Jet - When L pressure approaches a Mt range and gets stuck, the pressure
gradient drives low-alt wind parallel to Mt. range from low to high P.
Chinook (NA) & Foehn (EU) - When cold air shallow enough to be dammed behind the
Mt.range, warm air atop flows down compressed by increasing P causing air to warm ->
strong, warm, dry downslope wind (Foehn wall = clouds evaporating before starting the
warm descent)
Bora - Cold air deep enough that top is higher than Mt. -> cool, dry, downslope wind
Standard atmosphere - Avg variations of P, T, density with altitude
Troposphere - Concerns almost all weather. T decreases almost linearly w/ H. Top is
called Tropopause. (<11km)
Stratosphere - T is constant at first then gets warmer as it approaches Stratopause
Warm due to ozone layer absorbing UV light.
Modern aircrafts fly here to avoid storms and weather. (47km>x>11km)
Mesosphere - Temperature again decreases after stratosphere.
Top = Mesopause
Thermosphere - T increases w/ height. Beyond this point is exosphere where air is so
thin, does not behave like gas. Avg distance btw molecules = mean-free path.
Natural Mt. wave λ depends on - mean wind speed (M) & Static stability (S)
High M = High λ
High S = Low λ
Fronde # - Natural Mt. wave λ / Mt. width
Fr << 1 : When low M , high S, Weak Mt. wave
Fr = 0 : Most violent
Fr >>1 : weak amplitude, high λ
Fr = ∞ : high M, low S, strong turbulent wake behind Mt, but not much Mt waves.
2025/2026
Forms from collision of small ice crystals & hailstones (graupels)
Small ice crystals (+) carried to the top of TS by updraft to anvil while larger graupel (-)
towards bot as they fall.
When the voltage dif. is big enough, insulative air ->ionized, conductive. Greater build
up of voltage = longer lightning
P-static - Sparks on the outside of aircraft from contact with uncharged particles and (-)
builds up on the surface.
(St. Elmo Fire = corona discharge as filaments of light writhing on the outside).
Cumuliform clouds - Warm humid air rising through cooler surrounding air. Strong
updrafts.
S - Cumulus humilis
M - Cumulus mediocris
L - Cumulus congestus
XL -Cumulonimbus/TS
Happens when air near ground is colder than the ground (clear day w/ sunshine).
Happens behind cold front. *btw updrafts are weaker downdrafts of clear air. downdraft
causing wind gusts leading to darker patches of water = "cat's paws"
Stratiform clouds - Warm air slides up along cold air. Seen ahead of warm front. Not
usually turbulent but may have supercooled liquid.
H - Cirrus, Cirrostratus, Cirrocumulus
M - Altostratus, Altocumulus
L - Stratus, Nimbostratus
It goes H - M - L (w/ light rain or snow) in sequence.
Stratus vs Nimbostratus - Nimbo (diffuse) precipitating while Stratus is not (well
defined).
Castellanus - Special cloud
Look like small castle turrets, sign of atm becoming unstable, TS possible later. Cloud
diameter similar to height.
A thin cold air layer above warm air -> warm air rises -> warm-cold-air sandwich ->
castlellanus, a type of stratiform cloud.
Convective circulations do not touch the ground, contained in warm-cold air sandwich.
Racist Joke - A black Jewish boy runs home from school one day and asks his father,
"Daddy, am I more Jewish or more black?" The dad replies, "Why do you want to know,
son?" "Because a kid at school is selling a bike for $50 and I want to know if I should
talk him down to $40 or just steal it!"
Yomama Joke - Yo mama so stupid, she sold her car for gas money.
,Billow (Kelvin Helmholz Waves) clouds - Indicative of wind shear & CAT, smooth air
often above or below.
Wind shear causes waves in a cooler layer under warmer air. Short wavelength, thin
waves.
Parallel bands of clouds form at each crest of waves only when rising cool air is humid.
Associated with unstable air along with castellanus.
Lenticular (Mt-wave) Cloud - Indicates vertical wind oscillation & possible Mt wave
turbulence. Wind hits Mt -> rises and comes back down, overshoots due to inertia ->
rises again.
In the upward portion, air cools -> cloud. When it descends, cloud evap. Clouds appear
stationary -> "standing lenticular". First wave over Mt = "Cap Cloud"
Rotor Clouds - Turbulent clouds that form under crest of Mt waves.
Rotate about a horizontal axis parallel to Mt range. Associated w/ strong turbulence &
violent up/down drafts. Change in wind direction over short distance makes flying
extremely dangerous.
Banner Clouds - Mt. special cloud along with lenticular & rotor clouds.
Forms on downwind side of Mt. Wind causes low P on the other side of the Mt peak,
sucking up lower alt air -> vapour condenses to clouds.
Pyrocumulus & Pileus - Pyrocumulus: forest fires & volcanoes, heat & moisture may
lead to TS.
Pileus: Form over fast-growing cumulus clouds, harmless, shore-lived til cumulus rises
through.
Fractus clouds - Low-alt, ragged cloud aka scud. Indicates high humidity and strong
wind at low alt. Forms when; (1) rain falls into cloud-free air -> evaporates ->
recondenses into cloud (if cloud touches ground = precipitation fog). (2) humid, cool air
near ground lifted up by turbulence to lifting condensation level -> clouds form.
Clouds formed by extra heat, updraft, turbulence - Pyrocumulus, Pileus, Fractus clouds
Man-made clouds - Fumulus - clouds over cooling towers.
Contrails - Aircraft condensation trails, formed from water vapor from jet engines, drawn
into wingtip vortices, indicate strong wake turbulence.
Cross Winds & Tail Winds & Head Winds - Tail winds are good for travel but bad for
take-off/landing.
Crosswinds can be compensated by crabbing but bad for take-off/landing.
Try to land/take-off on a runway w/ # closest to wind direction for a headwind (i.e. 14 =
135o).
, Wind shear - change of wind speed &/ direction w/ altitude. Stronger when near-surface
winds are faster. Wind shear near ground may make landing and take-off difficult. There
are strong vertical shear in warm (ahead) & cold fronts (behind).
Can be caused by weather system - synoptic scale/convective shear OR Mt winds - Mt
waves, wind channeling, downslope windstorm. OR turbulence behind obstacle OR
aircraft.
Gap Winds - TRapped cold air flowing at high speed through passes & gaps. Also
applies down narrow fjords or straits. Strongest when cold air trapped under a strong T
inversion.
Barrier Jet - When L pressure approaches a Mt range and gets stuck, the pressure
gradient drives low-alt wind parallel to Mt. range from low to high P.
Chinook (NA) & Foehn (EU) - When cold air shallow enough to be dammed behind the
Mt.range, warm air atop flows down compressed by increasing P causing air to warm ->
strong, warm, dry downslope wind (Foehn wall = clouds evaporating before starting the
warm descent)
Bora - Cold air deep enough that top is higher than Mt. -> cool, dry, downslope wind
Standard atmosphere - Avg variations of P, T, density with altitude
Troposphere - Concerns almost all weather. T decreases almost linearly w/ H. Top is
called Tropopause. (<11km)
Stratosphere - T is constant at first then gets warmer as it approaches Stratopause
Warm due to ozone layer absorbing UV light.
Modern aircrafts fly here to avoid storms and weather. (47km>x>11km)
Mesosphere - Temperature again decreases after stratosphere.
Top = Mesopause
Thermosphere - T increases w/ height. Beyond this point is exosphere where air is so
thin, does not behave like gas. Avg distance btw molecules = mean-free path.
Natural Mt. wave λ depends on - mean wind speed (M) & Static stability (S)
High M = High λ
High S = Low λ
Fronde # - Natural Mt. wave λ / Mt. width
Fr << 1 : When low M , high S, Weak Mt. wave
Fr = 0 : Most violent
Fr >>1 : weak amplitude, high λ
Fr = ∞ : high M, low S, strong turbulent wake behind Mt, but not much Mt waves.
