ATPL Meteorology - Class 6: Clouds.
Summary
TLDRThis meteorology class explores cloud formation, starting with the basics of condensation and the dew point. It explains how clouds form from air cooling and water vapor condensing, influenced by dry and saturated adiabatic lapse rates. The video covers various cloud types, from high-level cirrus to low-level cumulonimbus, and their association with weather conditions. It also discusses cloud stability, the environmental lapse rate, and how these factors affect cloud cover and visibility for pilots, concluding with the significance of cloud classification in weather reports.
Takeaways
- 🌧️ Clouds form due to the process of condensation, where water vapor cools and changes from a gas to a liquid state.
- 🌡️ The dew point is the temperature at which air reaches saturation and water vapor starts to condense.
- 🧊 If the dew point is below freezing, water vapor can sublimate directly into ice crystals, forming around impurities or remaining as supercooled droplets until an impurity is introduced.
- 🌬️ Adiabatic cooling occurs when air expands and cools due to a drop in pressure, separate from the cooling caused by the surface temperature.
- ⬆️ As air rises, it cools at a rate of 3 degrees per thousand feet (dry adiabatic lapse rate) until it reaches the dew point, after which it cools at 1.8 degrees per thousand feet (saturated adiabatic lapse rate).
- 🌫️ Fog and mist are forms of low clouds that form when air is cooled near the surface, rather than through adiabatic rising.
- 🏞️ Air rises due to being warmer, orographic lifting by geographic features, or when encountering a front of colder, denser air.
- 🌟 Stability of air is determined by comparing the environmental lapse rate to the adiabatic lapse rates, which affects whether air will continue to rise, sink, or remain stable.
- 🌦️ Clouds are categorized by their stability (stable or unstable), height (low, mid, high), shape (stratiform or cumuliform), and the type of precipitation they produce.
- 📊 Cloud cover at aerodromes is reported in 'oktas', with full coverage being overcast and clear skies reported as 'SKC'.
Q & A
What is the fundamental concept behind cloud formation?
-The fundamental concept behind cloud formation is condensation, which is the process of water vapor cooling to the point where it changes from a gas to a liquid state.
What is the dew point and how does it relate to cloud formation?
-The dew point is the temperature at which the saturation vapor pressure matches the actual amount of water vapor in the air, leading to condensation. This is where water vapor starts to condense, marking the beginning of cloud formation.
How does the temperature change as air rises and its effect on cloud formation?
-As air rises, the pressure drops, causing the air to expand and cool. This cooling is known as adiabatic cooling, which occurs at a rate of 3 degrees per thousand feet for dry air and 1.8 degrees per thousand feet for saturated air, influencing cloud formation.
What is the difference between dry and saturated adiabatic lapse rates?
-The dry adiabatic lapse rate is 3 degrees per thousand feet and occurs when the air is not saturated, while the saturated adiabatic lapse rate is 1.8 degrees per thousand feet and occurs when the air is saturated and water vapor starts to condense.
Why do clouds form at different altitudes?
-Clouds form at different altitudes based on the temperature and dew point. The altitude at which the air cools to the dew point determines the cloud base, with different types of clouds forming at low, mid, and high levels.
What role do impurities play in the formation of ice crystals in clouds?
-Impurities in the air, such as smog particles or dust, provide a surface for ice crystals to form when the temperature is below freezing. Without impurities, supercooled water droplets may form and only freeze when they encounter an impurity.
How does the environmental lapse rate affect the stability of the atmosphere and cloud formation?
-The environmental lapse rate compares to the adiabatic lapse rates to determine atmospheric stability. If it's lower than both dry and saturated adiabatic lapse rates, the atmosphere is stable, but if it's higher, the atmosphere is unstable, leading to more cloud formation.
What are the two broad categories of clouds and how do they differ?
-The two broad categories of clouds are stable and unstable. Stable clouds are widespread and low, associated with light precipitation, while unstable clouds are tall and fluffy, associated with heavier showers and turbulence.
How are clouds classified by height and what are the categories?
-Clouds are classified by height into low-level clouds (up to 6,500 feet), mid-level clouds (6,500 to 23,000 feet), and high-level clouds (above 23,000 feet).
What does it mean when clouds are described in terms of 'octas' in aviation?
-In aviation, clouds are described in terms of 'octas' or eighths to indicate the amount of sky covered by clouds overhead an aerodrome, ranging from clear sky to overcast.
Outlines
🌟 Introduction to Cloud Formation
The paragraph introduces the topic of cloud formation, explaining the process of condensation where water vapor cools down and changes from gas to liquid form. The dew point, the temperature at which air can no longer hold water vapor and condensation occurs, is discussed. The text also covers the concepts of adiabatic cooling, where air cools as it rises due to reduced pressure, and the different lapse rates for dry and saturated air. The importance of understanding humidity is emphasized, and the viewer is encouraged to review previous content on this topic.
🌤️ Estimating Cloud Base and Fog Formation
This section delves into how to estimate the cloud base using temperature and dew point data, and discusses the formation of fog and mist. It explains that fog forms when air is cooled by a cold surface, leading to condensation without the need for air to rise. The difference between fog and mist is also clarified, based on visibility levels. The paragraph further explores why air parcels rise, including due to temperature differences or geographic features like mountains, and introduces the concept of atmospheric stability, which affects cloud formation.
🌡️ Atmospheric Stability and Cloud Types
The paragraph discusses the three types of atmospheric stability: absolute stability, absolute instability, and conditional stability, which depend on the environmental lapse rate compared to the adiabatic lapse rates. It explains how these conditions affect whether air parcels rise or sink. The categorization of clouds into stable (stratiform) and unstable (cumuliform) types is introduced, along with the basic characteristics of these cloud forms. The importance of understanding cloud types for pilots, in terms of weather conditions and visibility, is highlighted.
☁️ Detailed Cloud Classification
This section provides a detailed classification of clouds based on height (low, mid, high), shape (stratiform, cumuliform), and the type of precipitation they produce. It describes various cloud types, including cirrus, altostratus, altocumulus, nimbostratus, stratus, stratocumulus, and cumulus, along with their associated weather conditions. The paragraph emphasizes the importance of cloud cover reporting in eighths for pilots, which helps in assessing weather conditions at aerodromes.
🌦️ Cloud Cover and Weather Reporting
The final paragraph summarizes the importance of condensation at the dew point and adiabatic cooling in cloud formation. It revisits the concepts of stability and instability in the atmosphere and their impact on cloud formation. The classification of clouds is reiterated, with a reminder of the various types and their characteristics. The paragraph concludes with a discussion on cloud cover reporting in terms of octas (eighths of the sky) and the distinction between cloud ceiling and cloud base, which are crucial for aviation weather reports.
Mindmap
Keywords
💡Condensation
💡Dew Point
💡Adiabatic Cooling
💡Cloud Formation
💡Saturated Adiabatic Lapse Rate
💡Cirrus Clouds
💡Cumulus Clouds
💡Stratus Clouds
💡Orographic Lifting
💡Cloud Cover
Highlights
Clouds form due to condensation, where water vapor cools and changes from gas to liquid form.
The dew point is the temperature at which air reaches saturation and water vapor starts to condense.
Sublimation occurs when the dew point is below zero degrees Celsius, leading to the formation of ice crystals.
Supercooled water droplets form when there are very few impurities in the air, and they can remain liquid below freezing point.
Adiabatic cooling is a secondary temperature reduction caused by the expansion of air as it rises.
The dry adiabatic lapse rate is 3 degrees Celsius per thousand feet, indicating the rate of cooling due to adiabatic expansion in dry air.
The saturated adiabatic lapse rate is 1.8 degrees Celsius per thousand feet, which applies when air is saturated with water vapor.
Clouds are formed as air parcels rise and cool adiabatically, condensing water vapor at the dew point.
Fog or mist is a low cloud formed when air is cooled at the surface, without the adiabatic rising process.
Air rises due to being warmer, or due to geographic features like mountains, or when it encounters a colder air mass.
Stability of air is determined by comparing the environmental lapse rate with the adiabatic lapse rates.
Absolute stability occurs when the environmental lapse rate is lower than both adiabatic lapse rates, leading to sinking air.
Absolute instability happens when the environmental lapse rate is higher than both adiabatic lapse rates, causing air to rise.
Conditional stability depends on whether the air is dry or saturated, influencing whether air rises or sinks.
Clouds are categorized by height into low, mid, and high level clouds, and by shape into stratiform or cumuliform.
Cirrus, altostratus, and nimbostratus are examples of clouds associated with stable weather conditions.
Cumulus and cumulonimbus clouds are associated with unstable conditions and can lead to showers and thunderstorms.
Cloud cover is reported in eighths, or octas, to describe the amount of sky covered by clouds at an aerodrome.
Cloud base and cloud ceiling are terms used to describe the height of the lowest and highest clouds respectively.
Transcripts
i'm sure we have all looked for cool
shapes and objects in the clouds when we
were younger i know i did at least but
how do these cool shapes and objects
form in the sky
let's find out
[Music]
hi i'm grant and welcome to the sixth
class in the meteorology series we've
now finished looking at the basic
elements of the atmosphere we're going
to be moving on to the more interesting
weather aspect of meteorology
in this class we're going to be taking a
look at how clouds are formed and how we
describe them and this class requires a
good understanding of how humidity works
so if you haven't done so i'd recommend
going back and watching the previous
video all about humidity before getting
started on this one
the fundamental concept behind why
clouds form is due to condensation which
is the process of water vapor cooling to
the point where it is no longer in gas
form but now in liquid form
this happens because the air cools down
and the individual water molecules lose
energy and start to be attracted to each
other and when the particles are close
together they form chains of these
particles which in on the atomic level
is how
liquid states are formed so that's why
we get liquid water when we cool down
the temperature at which this
condensation occurs is known as the dew
point
this is the temperature where the
saturation vapor pressure the amount of
water the air that can hold what amount
of water vapor the air can hold
reduces down to the point where it
matches the actual amount of water in
the air known as the actual water vapor
pressure
when the temperature of this dew point
is above zero degrees celsius in this
example we've chosen 10 degrees celsius
we would form
it's the
liquid water molecules in the air
if the dew point was below
zero degrees celsius then we would
sublimate we would go through the
sublimation process
straight into the solid water state in
ice form ice crystals form around
impurities in the air
so if you're in the situation where
there are very few impurities near such
as like smog particles or dust particles
then you can end up with something
called supercooled water droplets
and these are just extremely cold
droplets of water
and they will only form into ice when an
impurity is introduced
this can happen for example when an
aircraft flies through a cloud full of
super cold water droplets that aircraft
is then the impurity in the air that the
supercooled water droplets would need to
form ice and that could be maybe the
leading edge of the wing for example
when air rises the pressure drops and so
does the temperature as we get further
and further from the surface
because of the pressure drop the air
will also expand because there's
obviously less pressure to push it all
together
if we ignore the temperature reduction
caused by moving away from the surface
and only look at the pressure reduction
there is then a secondary temperature
reduction which is caused by the
expansion of the air
this secondary temperature reduction
happens all the time as parcels of air
rise and fall and it happens
independently of this actual temperature
changes
caused by the surface being warmer than
it is higher up
and this secondary temperature cooling
process
we call an adiabatic cooling process
adiabatic
so as a parcel of air rises and cools
adiabatically due to that expanding
air and dropping pressure it does this
at a rate of three degrees per thousand
feet so if we have a parcel of air
rising up every thousand feet that
parcel of air will cool just because of
the secondary effect by three degrees
every thousand feet this is known as the
dry adiabatic latch rate
so it's dry because it's
below the saturated humidity it's below
a relative humidity of 100
when it cools down to the dew point and
the air now becomes saturated it then
cools adiabatically at a different rate
which is known as the saturated
adiabatic lapse rate and this is 1.8
degrees per thousand feet the reason
behind this difference is because as the
water vapor starts to condense out into
liquid form at the dew point the heat is
given off heat is released in order to
change it to this liquid state and this
heating effect this heat being given off
um adjusts the temperature from 3
degrees up to 1.8 there's that latent
heat in the atmosphere that is stopping
it from three degrees and moving it more
towards 1.8
so hopefully you can start to see the
way that clouds are formed a parcel of
air rises up and cools down
adiabatically at the dry adiabatic lapse
rate of three degrees per thousand feet
this is until it reaches
the temperature where the air cannot
hold any more water vapor in it and it
becomes saturated the dew point
temperature
the water vapor then condenses out to
form the beginnings of clouds and as the
parcel of air continues to rise at the
saturated adiabatic lapse rate
of 1.8 per thousand feet
it paints more cloud as it goes just a
little paintbrush painting clouds as it
goes this means that you can estimate
the cloud base if you know the current
temperature and the dew point
in this example we're going from a
temperature of 16 degrees celsius and we
know that the dew point is 4 degrees
celsius
so it's a 12 degree change and we're
doing 3 degrees every thousand feet we
can estimate that the cloud base is
going to be up at 4 000 feet the actual
height of the clouds will depend very
much on the stability of the atmosphere
which we'll look at in a little bit
fog or mist is just very low cloud and
it's formed slightly differently to
regular clouds the main difference is
that the adiabatic rising and expanding
process doesn't occur
because the air isn't rising essentially
with fog the air is cooled down because
of a cold surface temperature through
conduction and radiation heating and
stuff like that
with fog the air is cooled because of
the cold temperature and that brings the
saturation vapor pressure down until it
meets the actual amount of water vapor
pressure in the air which is known as
the dew point
at this dew point all the water vapor in
the air condenses out to form clouds and
the small water and ice particles are
lifted and mixed through the air by wind
and the cool surrounding air causes yet
more
water vapor to condense out
and depending on the temperature and the
amount of mixing going on fog can be a
couple of feet off the ground to a
couple of hundred or a couple of
thousand feet even
the only difference between mist and fog
is the level of visibility inside it
fog is considered the visibility less
than a thousand meters and missed is
when the visibility is less than 5000
meters
so why does a parcel of air rise
the most basic one is considering warm
air
so warm air rises because it expands the
volume increases and that makes the
density decrease
and less dense things float on top of
more dense things so hot air will rise
because of this reason
air can also be caused to rise by
geographic features such as mountains
which is known as orographic rising
another way that it can rise is when you
reach the
front of a colder band of air colder air
is more dense and you come in the air
comes in not you come in the parcel of
air comes in and is will automatically
be
less dense than a colder section of air
so it will rise up because of that
depending on the relative density
of the air
compared to its surroundings it will
either continue to rise known as
unstable air it will descend which is
known as stable air or it will stay
exactly where it is in neutral
equilibrium
the density of the surrounding air is
also going to be dependent on
temperature such as the heating process
that we saw
and the way that this works is that the
rising parcel of air will cool at the
dry adiabatic lapse rate or the
saturated
adiabatic lapse rate
and we compare that to what is known as
the environmental lapse rate
so this would be
um if we're looking at our international
standard atmosphere this is the two
degrees per thousand feet
but
depending on the day and the conditions
this is going to be slightly different
so when we compare these two we can find
out if the saturated sorry if the rising
parcel of air is more dense or less
dense compared to its surroundings and
if it is less dense it will continue to
rise and if it is more dense it will
start to sink down and be more stable
so the best way to think about these
stability in general is to compare the
three main types
the first one is known as absolute
stability
so this means that the temperature of
the parcel of air must always be
warmer than
the
environmental air surrounding it
so in this diagram here we've used an
environmental latte of one degrees per
thousand feet
this means that as a parcel of air rises
it will always be cooling down at a
faster rate of either three degrees for
the dry
or 1.8 for the saturated
this means that wherever we look at the
altitude the rising parcel of air is
always going to be
colder and therefore more dense
and it will tend to sink rather than
rise
so for absolute stability you need the
environmental latch rate to be lower
than both the saturated and the dry
adiabatic lapse rate
one degree needs to be below 1.8 in
essence
the opposite case to this is absolute
instability
this means that the temperature of the
parcel of air must always be hotter than
the surrounding environmental air to
make it less dense and to rise up
this happens when the environmental
artery is larger than both the dry and
saturated adiabatic lapse rate
so if we have look at this example and
we have an environmental latte of four
degrees every thousand feet
then if we start off at a sea level
temperature of 18
the rising parcel of air will reach a
temperature of
12 degrees at 2 000 feet because it's
three degrees every thousand feet six
degree difference
while the surrounding air
will cool down to 10 degrees
because it's cooling four degrees every
thousand feet
this means that our
parcel of air that's rising is hotter
and it's going to continue to rise when
the air becomes saturated it then starts
to cool up 1.8 degrees per thousand feet
and by the time we reach 4000 feet we're
going to be at
8.4 degrees
and by this point the surrounding air is
going to be all the way down at 2
degrees
so again the rising parcel of air is
warmer it will continue to rise the
third type of stability is conditional
stability and this is can the condition
in this case is whether the air is dry
or saturated so if the parcel of air is
unsaturated it will be colder than the
surrounding air
and it therefore sinks down
if the parcel of air is saturated it
will then become warmer than the
surrounding air and keep rising
this will happen when the environmental
artery is between the dry and saturated
adiabatic lapse rate
if we think about it in this example of
two degrees for every thousand feet
then if we start at a temperature of 10
degrees celsius at 2000 feet we're going
to be at
4 degrees celsius
and the surrounding air the
environmental lapse rate will be six
degrees celsius
so
the rising parcel of air is more dense
it will tend to sink down
once we become saturated however
the temperature would only drop by 1.8
degrees and it would start to become
initially it will be
reducing the gap between them and
eventually they will cross over
and the environmental lapse rate
and the saturated adiabatic lapse rate
will
flip in essence and you'll have the
rising parcel of air always be warmer
than the environmental lapse rate and it
will continue to rise
as humans we like to categorize things
and clouds are no different
generally speaking though they fall into
two broad categories which are either
stable or unstable
stable clouds will be what we call
stratiform which means very
short not very tall and very widespread
they are associated with light
continuous precipitation
poor visibility and light turbulence
because there's not that much air rising
to cause that turbulence
the other type is unstable clouds which
are what we call cumulform
which means they're tall and fluffy
basically
they're also associated with showers of
precipitation
but good visibility but again we've got
that moderate to heavy turbulence
because there's lots of air rising to
cause it
you'll never really hear cloud types
described as stable or unstable
and because there's a lot more specifics
that we can get into as you can see
the first one to talk about is the
height of clouds
if the cloud base the bottom of the
cloud is up to six thousand five hundred
feet we call these low level mid level
is six thousand five hundred to two
twenty three thousand
and high level clouds would be above
twenty three thousand then you can
describe them again in terms of shape
in terms of cirrus which means like
quite wispy
or cumulus which means that kind of
fluffy shape that you would typically
think of when you think of a cloud and
then you can
combine and cross different types of
these clouds to form the main categories
here as i'll quickly run through
i've tried to draw them very badly so
it's probably if you're very interested
to see what type they are just have a
quick google and you'll see that my
drawings are rubbish so starting off
with the high level clouds cirrus clouds
cirrostratus and cirrocumulus
so cirrus are like feathery sort of
shapes
and
cereal stratus are like mesh of fibers
kind of like a hazy sort of look
and ciro cumulus are small bubbly clouds
and they're all con associated with
relatively stable conditions apart from
the serocumulus which will have little
unstable patches where the little
bubbles fall
and because they're so high up there's
no precipitation from any of them
mid-level clouds have the prefix of alto
that's a good way to remember mid-level
clouds and they fall into either the
strata form or the cumulative form
stratiform being the low
and widespread and cumulative form being
more fluffy more um more height to them
so altostratus would be kind of grey
blue colours and quite large associated
with stable conditions and maybe give
you some light continuous precipitation
altocumulus would be white gray with a
few bumps of cumulus looking things
and that means that there's going to be
unstable little parts within it
and that's associated with light showers
as well then you come on to the
low-level clouds where you see a lot of
precipitation this is where most of the
precipitation is formed
first one of these is nimble stratus
that's your kind of gray
and overcast condition sort of clouds
associated with stable conditions and
you'd get moderate continuous
precipitation out of them
you could have stratus clouds as well
that's a
a gray sort of layer
to be quite stable conditions and you
get continuous light so not as
developed as a nimbo stratus think of
that as like a rain cloud continuous
rain all day that may be a chance of
rain
stratocumulus clouds are patchy white
and that means there's a few unstable
patches and you have the potential for
continuous light precipitation
cumulus clouds are your fluffy low
clouds good for you know spotting shapes
in and stuff like that
associated with unstable conditions
and expect moderate showers if any
precipitation
and then the daddy of them all
cumulonimbus clouds these are your big
high developed putting them in a low
level cloud because of the low base but
they can extend all the way up to the
levels of high level
they can be
all the way up to the
uh troposphere tropopause even
uh up to that you know 36 000 feet these
can be very very large clouds
and
they are storm clouds essentially very
unstable associated with heavy showers
lightning
uh not in good conditions basically so
there's a whole world of cloud types and
classifications to jump into if you're
interested but an important factor for
us pilots is the amount of cloud cover
we would like to know if it's going to
be a blue sky day or overcast so we
basically know when to pack our nice
sunglasses or not
it's also kind of useful for telling us
the weather conditions at an aerodrome
so
we will then be able to work out if we
are able to land there or not
the cloud cover is reported to us in
terms of eighths of the sky
overhead the aerodrome which is known as
an octa one-eighth is equal to one octa
and if you imagine this is the the land
that the aerodrome takes up just divide
that into eight sections and that is how
you decide how much cloud cover is
overhead in aerodrome this is something
we're gonna get into a bit more in terms
of when we look at weather reports
towards the end of this uh series
but just for now know that it's eighths
of the sky and there's different regions
uh different ranges for
the amount of cloud cover you get zero
which is known as clear sky sky clear
skc is given a little designator on
weather reports one to two is few three
to four is scattered five to seven is
broken and eight is overcast
and if the sky is more than fifty
percent covered so these bottom two
you call it a cloud ceiling
whereas if it's the
uh below fifty percent ones zero one
well not zero but one to two or three to
four you would call that a cloud base
so you would see a report on airdrome
will tell you various weathers and i
would say
there's few clouds at
1500 feet so you could say the cloud
base is at 1500 feet
in summary then so condensation happens
at the dew point and this is where the
saturation vapor pressure
reduces to the actual vapor pressure
that we have in the air and the water
starts to condense out
if the dew point is lower than zero then
the water can sublimate straight into
ice and these ice crystals will form
around impurities if there's no
impurities it will sublimate uh well it
won't submit it will just form very cold
extremely cold supercooled water
droplets which will then form ice when
introduced to an impurity such as an
aircraft
adiabatic cooling is the separate
secondary cooling which is caused by the
expansion of air think of it as like
when you
spray a can of if you've got compressed
air for cleaning out a computer or
something like that that gets very cold
because the air is expanding and cooling
down
the rate of cooling that happens with
this expansion is dependent on the air
and if it's dry or if it's saturated the
dry adiabatic latte is three degrees per
thousand feet and the saturated
adiabatic latter is 1.8 degrees per
thousand feet clouds form
by these
air pockets these parcels of airs
cooling down to the dew point due to
that dry adiabatic lapse rate due to
rising of that dry adiabatic labs rate
and then they will continue to rise at
the saturated adiabatic lapse rate and
depending on the environmental lapse
rate will either have
stable conditions
in stable conditions or conditional
conditions
so absolute stability is when the
environmental latter ray is lower than
both the saturated and the dry adiabatic
latex rate so that means it's going to
be a value of less than 1.8 degrees per
thousand feet that means that the
temperature of the air parcel is always
going to be colder than the surrounding
environmental air and therefore more
dense and it's going to be
more stable
the opposite of that is absolute
instability
when the air
environmental latch rate is larger than
the dry adiabatic latex rate and the
saturated adiabatic lapse rate and that
means that a rising parcel of air the
dry or saturated rising parcel of air is
always going to be warmer than the
surrounding air less dense it's going to
rise up
and then you've got conditional which is
between the two
and basically depends if the air is dry
it will be more stable and if it's
saturated it will become it unstable
clouds can be classified in loads of
different ways
and there's basically a few categories
that you think if you think of a stable
versus unstable stable
low
widespread clouds unstable quite high
fluffy clouds then you think about the
height you've got the low mid or high
levels think about the shape
you've got the stratiform shape or
you've got the cumulo
cumulus shape
then you've got the types of
precipitation
and
nimble usually means
wet i don't know what the actual word
means but if it's nimble stratus that
means it's going to be moderate
um
moderate rain whereas if it's just a
stratus it might not be quite as heavy
rain
classification is a bit weird because
there's a lot of crossover and it's hard
to tell
when a stratus becomes a nimble stratus
there's no like defining thing
so
cloud classification come with a pinch
of salt
and then when we're looking at cloud
reports or weather reports for
aerodromes we'll see it described in
terms of octas which means eighths and
if the aerodrome is covered by no clouds
you will say it's sky clear
if it's one to two of these eights that
are covered it'd be few three to four is
scattered five to seven is broken and
eight is overcast
and when there's more than 50 percent of
the
uh space over the air drone covered in
clouds is known as a cloud ceiling so
broken and over classic cloud ceiling
and
not sky clear because obviously there's
none but one
to four few and scattered you would call
that a cloud base
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