ANSWERS 2025/2026
what are layer/stratiform (ST) clouds associated with - warm fronts (because the warm
air moving over a wedge of cool air, causing the warm air to slide along the cold air
because of its buoyancy is typical of warm fronts); stratiform clouds can be often found
along warm frotns
what are the categories of strati form clouds - high, middle, and low
high = cirrus, cirrostratus, and cirrocumulus
middle = altostratus and altocumulus
low = stratus and nimbostratus
what type of cloud is the halo associated with - cirrostrratus, which is in the category of
high for stratiform clouds
what type of cloud is a corona associated with - altostratus clouds, which is in the
middle category of stratiform clouds
what is the difference between stratus and nimbostratus clouds - both appear the same
because they have low cloud bases and are dark but nimbostratus are precipitating and
stratus is not; stratus also looks more textured whereas nimbostratus looks more
diffused/soft because of the precipitation
what are the hazards associated with layer/stratiform (ST) clouds - - not usually
turbulent so you can fly smoothly through them
- need to fly IFR inside it (like any other cloud)
- if it is cold enough, ice can form on the edges of the aircraft because of supercooled
droplets
what are the types of special clouds - castellanus, billow, lenticular, rotor, banner, and
fractus clouds, pyrocumulus, pileus, fractus, fumulus, contrails
castellanus clouds - - a type of special cloud
- happens when a thin layer of cold air forms above a thin layer of warm air, which is
statically unstable because warm air rises and cool air sinks because it is more dense
- are a type of stratiform cloud
come in high, medium, and low
- will be very turbulent
- indicate a thunderstorm might be coming
,billow (k-h wave) - - type of special cloud caused by wind shear (change of wind speed
or direction with height) in the atmosphere which causes waves to form in a layer of air
where cooler air underlies warmer air
- indicate wind shear and CAT
- short and thin
- look like an accordian
- can break and cause cat eye swirls
- can be high or mid
- do not need mountains to form
- cirrocumulus undulatus = high billow
- altocumulus undulatus = mid billow
what special clouds are associated with strong winds across mountains - lenticular,
rotor, banner
what special clouds are associated with unstable air loft - castellanus, billow (k-h wave)
describe lenticular clouds characteristics - - type of special cloud associated with strong
winds across mountains
- look like UFOs or dinner plates stacked
- form in the crests of mountain waves if the air is humid
- pilots would experience updrafts and downdrafts in these types of clouds
- aka mountain wave cloud, lee-wave cloud
what is a cap cloud - a lenticular cloud that is the first one in the sequence which is on
top of the mountain and looks like a hat (cap)
describe rotor cloud characteristics - - type of special cloud associated with strong
winds across mountains
- violent turbulence which can damage/break aircraft
- ragged and usually under the crests of mountain waves
- they rotate
- usually under lenticular clouds (I think?)
if you do not see any lenticular or rotor clouds by a mountain, is it safe to fly? - no, there
can still be dangerous waves and rotors
describe banner cloud characteristics - - a type of special cloud associated with strong
winds across mountains
- form on the downside of mountain peaks
- indicate strong turbulence
what are clouds which are formed by extra heat, updrafts, or turbulence - pyrocumulus,
pileus, fractus/scud
pileus clouds - - special cloud
,- form over fast growing cumulus clouds
- harmless and don't affect anything
describe pyrocumulus clouds - - type of special clouds that form because of extra heat,
updrafts, or turbulence
- form over forest fires and volcanoes
- indicate a forest fire so strong that the heat and moisture released can make a
thunderstorm in the smoke
- occurs over a cumulus congestus (large convective/cumiliform CU cloud) so you can
anticipate strong updrafts, turbulence, and maybe a thunderstorm later
describe fractus/scud clouds - form in turbulent humid air near the ground; indicate high
humidity (such as due to drizzle falling from higher clouds) and strong winds at low
altitude
what clouds are made by humans - fumulus (cumulus homogenitus) and contrails
(cirrus homogenitus); these are types of special clouds
describe fumulus clouds - - aka cumulus homogenitus
- water-droplet clouds over cooling towers
contrails (cirrus homogenitus) - - aircraft condensation trail; indicate turbulent wing-top
vorticles behind aircraft
- small aircraft can be flipped upside down if they accidentaly fly into a wing-tip vortex
- military pilots hate these because it reveals aircraft to the enemy
What order do stratiform clouds appear in the sky (they all have different altitudes); the
layer of clouds you would see if a warm front approached - (highest to lowest) cirrus,
cirrostratus, cirrocumulus, altostratus, altocumulus, nimbostratus, stratus
what pilots must stay out of clouds - pilots flying VFR (visiual flight rules) but even IFR
pilots are concered if there is a low overcast (ceiling) for their destination airport
sky cover/cloud cover/cloud amount - the fraction of the sky covered by cloud;
measured in oktas
METAR - Meteorological Aviation Reports
ceiling - the lowest broken or overcast clouds
what do you report as the ceiling if clouds are obscured - there might be clouds but the
observer cannot see them; in obscured situations, you report the vertical visibility (VV)
as a ceiling instead
, what is true of photos of sky cover taken at oblique angles? - you see the vertical sides
of next clouds so the cloudiness looks greater than it is; so consider that when giving
sky cover estimates for photos during exams
what should you keep in mind of your cloud cover estimates if you are at a lower level or
flying above/below/at an oblique layer - clouds at lower level altitudes block view of
higher altitude clouds that may or may not be there; you have to assume there are;
similarly, if you are flying above or below clouds, at your slant/oblique view, it will look
more overcast too
Define AGL - Above ground level; used to describe the height of a cloud (for example, a
cloud base of 1000 feet AGL)
weather observers never ____ cloud coverage but often ____ cloud coverage -
underestimate; overestimate
what is the type of visibility most relevant to safety when flying - horizontal visibility
(looking straight ahead); this is because vertical visibility (looking down) or looking at a
nearly vertical angle (slant visibility) might make the pilot be able to see the airport, but
once you descent and enter fog, it will make it hard to see.
if you hear the term visibility without any adjectives, what does it mean? - horizontal
visibility
describe horizontal visibility - - measured in canada as statute miles over land and
nautical miles over ocean
- us uses statue miles
- the world meteorological organization (WMO) uses km or metres
what affects visibility and makes it poor? - fog, haze, clouds, volcanic ash, dust, sand,
smoke/pulluted air
if visibility is poor, why does this affect pilots? - - can't see the ground for landmarks for
navigation
- other aircraft or obstacles
- the horizon, to help them fly the plane level
- the runway, for landing
why is poor visibility so dangerous? - even if a pilot sees poor visibility, the speed at
which the plane flies can make it a matter of seconds to move the aircrafy
VFR and IFR are related to what concept? - visibility
how is visibility measured? - - by human observers by trying to see a landmark of known
distances from the airport, like a tall tower, mountains, trees, etc.
- from automated instruments