Aerospace Education
Module 3
Air Environment
Contents
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Chapter 1 – Air Circulation
Chapter 2 – Weather Elements
Chapter 3 – Moisture and Clouds
Chapter 4 – Weather Systems and Changes
Quiz
Credits
Chapter 1
“Air Circulation”
Radiation
The method through which
the Sun heats the Earth is
called radiation. The energy
produced by the Sun radiates
into the Earth’s atmosphere
and this energy is absorbed
unevenly depending on the
surface or substance. About
50% of the solar radiation is
absorbed by the surface of
Earth, the other 50% is
reflected back and absorbed
by the atmosphere or
radiates back into space.
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Rotation and Revolution
The has two motions that
affect the amount of heat
received from the Sun.
These motions are it’s
rotation and revolution.
Our orbit around the Sun
is our revolution, which
takes 365 days, 5 hours
and 48 minutes. While it
revolves, the Earth is
tilted on it’s rotational
axis by 23.5°.
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This axis tilt causes the
length of days to vary as
well as cause our seasons.
As different areas of Earth
are tilted towards and
away from the Sun, they
receive less or more
energy from the Sun,
which we perceive as
seasons.
Rotation and Revolution
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The Coriolis Effect
The Coriolis Effect is a
result of the Earth’s
rotation. As the Earth
rotates on it’s axis, it
creates wind moving in
a counterclockwise
motion. This wind
causes objects moving
in a straight line North
or South to be deflected
to the West.
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Circulation
The uneven heating of
Earth causes the
movement of the air.
When on a global scale,
this is called the general
circulation of the
atmosphere, or
circulation. Basically, this
general circulation is the
world-wide system of
wind which transfers heat
from the tropical regions
to the polar regions.
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Circulation
The area of Earth which
receives the most energy
from the Sun is the equatorial
region. This energy shows
itself after moving about 30°
North or South of the equator
where the warmed equatorial
air begins sinking and moving
back towards the equator.
This causes steady, warm, and
almost continuous breezes.
The Coriolis Effect causes
these winds to curve to the
West. These winds are known
as the trade winds.
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Circulation
When the trade winds
converge on the
equatorial region, the
converging winds cause
a general upward wind
as the cooled air is
heated once more. This
causes the equator to
have no steady surface
winds. This calm,
equatorial region is
known as the doldrums.
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Circulation
As you move farther
North or South from the
equator, between 30° and
60° latitude, you
encounter winds blowing
towards the poles which
curve to the East. These
winds are known as
Prevailing Westerlies,
after the direction in
which they originate.
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Circulation
Once you reach
approximately 60° latitude in
either hemisphere, the
Prevailing Westerlies begin
joining with Polar Easterlies
to cause another upward
motion. The Polar Easterlies
form as the atmosphere over
the poles cools and sinks.
This air then spreads out
over the surface and is
curved to the west by the
Coriolis Effect. They receive
their name by their direction
of origin, the East
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The Jet Stream
The Jet Stream generally
crosses the United State at
about 30-35,000ft., moving
West to East. The Jet Stream
develops due to strong
temperature differences in
the upper troposphere.
These large differences
cause large pressure
differences, which in turn
create stronger winds than
usual. The Jet Streams
typically blow at between
120-150mph, with recorded
speeds of up to 450mph.
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It snakes for thousands of
miles across the United
States, hundreds of miles
wide and several miles
deep. During the Winter
months it is generally
stronger and moves
farther South. Aircraft
flight plans often take the
jet stream in mind and
use it to their advantage
or avoid it.
The Jet Stream
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Chapter 2
Weather Elements
Wind
Wind is a body of air in
motion which has direction
and speed. Wind direction
is determined by the
direction in which the wind
is coming from. Wind speed
is expressed in either miles
per hour or knots. 1 Knot is
1 nautical mile per hour. A
nautical mile is 6,076 feet,
or approximately 1.1 miles.
There are several ways of
estimating wind speed, such
as using a flag or the
Beaufort Scale.
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Wind
Wind, as the name
indicates, also causes
Wind Chill. As wind blows
away the warm air
directly around your
body, your body tries to
warm the air up again,
causing it to lose heat.
The harder the wind is
blowing, the faster the
warm air will be taken
away and the colder you
will feel.
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Wind
Wind has a vast multitude
of odd phenomena that it
shows itself in. One of these
phenomena is a microburst.
Microbursts have been
responsible for many
aircraft crashes, primarily
during takeoffs and
landings. Microbursts are
downdrafts associated with
unstable air, cumulus
clouds, and thunderstorms.
As these microbursts occur,
an aircraft entering one will
first encounter a stronger
headwind, causing more lift.
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To counter this, the pilot
will point the nose down
and decrease thrust. As the
aircraft flies through it, it
may encounter a tailwind,
pushing the nose down
even farther and reducing
lift. If the aircraft is close to
the ground, such as during a
takeoff or landing, it may
not have time to recover,
causing it to crash.
Wind
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Wind
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Temperature
Heat is the total energy
of all molecules within a
substance. Heat is also
extremely relative,
especially when
expressed in
temperature.
Temperature is a
measure of molecular
motion expressed on a
man made scale in
either Fahrenheit,
Celcius, or Kelvin.
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Celsius is the metric
measurement for
temperature, with 0° and
100° being water’s freezing
and boiling points. Kelvin is
a scientific measure, where
0° is absolute zero.
Fahrenheit is the English
system measurement for
temperature with 32° and
212° being water’s freezing
and boiling points.
Temperature
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Pressure
The push of the weight of the
atmosphere upon us is called
atmospheric pressure. Air
pressure is measured by a
mercurial barometer, an
aneroid barometer, or an
aneroid barograph. An aneroid
barometer is the easiest to read
and are often found in homes
and offices on walls. Mercurial
barometers are not as easy to
read, but are more reliable and
more stable. Aneroid
barographs give permanent
records of pressure and are
therefore found in weather
stations around the country.
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Chapter 3
Moisture and Clouds
Moisture
Moisture is absolutely pivotal
to our weather, it’s one of
the driving forces behind it.
Water vapor is always
present in our atmosphere to
some degree. As more and
more water vapor is in the
air, it begins becoming
saturated. The air becomes
saturated at different levels
of humidity at different
temperatures. The
temperature at which air
becomes saturated is it’s dew
point.
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Once an air mass is
saturated, any more
water vapor it receives
condenses into a liquid
form. This process is
called condensation.
Clouds and fog are both
products of condensation.
Fog
Fog is formed of tiny
droplets of liquid water
that is very close to the
surface. Fog generally
forms with the dew
point and temperature
are within 5 degrees of
each other and there is
little wind (>5kts). Fog
can limit visibility and
restrict takeoffs and
landings.
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Clouds
Clouds form in the same
way fog does, only off of the
surface. Clouds are a visible
indication of the weather
and what it is capable of
doing. There are three basic
forms of clouds, cumulus,
stratus, and cirrus. Clouds
are all classified their
appearance, height, and
basic form.
Cumulus are billowy,
puffy, and generally white.
They indicated good
weather. Stratus has a very
uniform appearance. They
are thin, sheet-like, and
they are generally gray.
Cirrus clouds are very high
and are thin, wispy, white
and look like thin filaments.
They are also mainly
composed of ice crystals
due to their height.
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Clouds
Cumulonimbus clouds are
storm clouds and are
avoided by pilots. They
can produce heavy rain,
strong wind, hail,
tornadoes, and thunder
and lightning. The main
threat to pilots however,
is turbulence. Turbulence
is the unrest or
disturbance of air.
Unstable air is very
turbulent whereas stable
air is very smooth.
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Cloud forms can provide
an indication as to
whether or not they
contain turbulence.
Cumulus clouds for
example, are formed by
convection, meaning the
rising and falling of air.
Therefore, pilots know
they will encounter
turbulence when flying
through cumulus clouds.
Clouds
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Chapter 4
Weather Systems and Changes
Air Masses
Air masses is a huge body of
air, generally 1,000 miles or
more across that have the
same temperature or
moisture characteristics.
The air masses are classified
by their source region’s
surface and the nature of
the source region. Air
masses are identified by a
two-letter code consisting
of a lower case and capital
letter.
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The lower case letter is
either an m for maritime or
c for continental. Maritime
signifies an oceanic air
mass, which are generally
moist. Continental signifies
a land air mass, which are
generally dry. The capital
letter is either P for Polar, A
for Arctic, T for Tropical, or E
for Equatorial. Polar and
arctic air masses are
generally cold and tropical
and equatorial air masses
are generally warm.
Air Masses
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Fronts
Fronts are classified as being either
Warm, Cold, Stationary, or Occluded.
Warm fronts occur when warm air
moves into an area of colder air and
subsequently collide. The warm air
then rises above the cold air mass as
it’s lighter. Cold fronts are also
generally faster moving that warm
fronts and therefore push warm air
masses out quickly. Fronts that
collide with each other, but don’t
have a sufficient enough temperature
difference to force each other out of
the way result in a stationary front.
These can last hours or days, but
eventually will end when a more
forceful air mass moves in.
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Occluded fronts involve 3 different
air masses and are classified as
either warm or cold. In a cold
occluded front, cold air moves in
and collides with warm air and
pushes it above it, the leading
edge of the front then collides
with a cooler air mass that doesn’t
rise because there isn’t sufficient
enough temperature difference.
The coldest air eventually forces
itself below the cool air with the
warm air on top. The opposite
happens in a warm occluded front
but creates the same results.
Fronts
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Thunderstorms
Thunderstorms are the
result of cumulonimbus
clouds, and, as their name
indicates, always possess
thunder and lightning. They
usually produce strong
wind, heavy rain, and
sometimes hail.
Thunderstorms have three
stages: building, mature,
and dissipating.
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The building stage is
characterized by strong
updrafts as the storm builds
and grows vertically. As
moisture climbs higher it
gets heavier and starts
falling, the updrafts are still
occurring however, so the
moisture travels up and
down several times, which
signifies the thunderstorm
is now mature. The
dissipation stage contains
downdrafts only.
Thunderstorms
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Thunderstorms
During thunderstorms, it
is important to stay
inside, away from
windows and doors.
Don’t use any electrical
appliances. Don’t use the
telephone, shower, or
water faucets as well.
Stay away from water and
metal objects in general.
Don’t stand in an open
field or near trees. If in a
group, stay low and
spread out. If you’re in a
car, stay in it.
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Tornadoes
Tornadoes are one of the
most severe weather
phenomena in the U.S.
and about 700 are
reported annually.
Tornadoes are formed by
unstable air of very low
pressure that usually
moves in a
counterclockwise motion.
Air is sucked into the
center and is rapidly lifted
and cooled.
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Tornado funnels appear
very dark due to dirt and
debris. They usually
touchdown for several
miles then go back up
into the cloud, only to
touch down again later.
Tornadoes are generally
50-500 yards wide and
move at an average speed
across the ground of
70mph.
Tornadoes
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Tornadoes
During a tornado it’s
imperative you get into a
basement or
underground. If a
basement isn’t available,
get into a ditch or low to
the ground. If indoors,
stay away from windows
and doors and move to
the center of the building.
If out in open country
only move in 90° away
from it.
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Tornadoes
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Hurricanes
Hurricanes can be
considered to be the most
dangerous type of storms
on Earth. They produce
numerous thunderstorms
and tornadoes within them.
Their winds are not as
strong as tornadic winds,
but they are still almost
always above 100kts and
last much longer while also
affecting a much, much
wider area.
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Hurricanes often cause
large amounts of coastal
flooding and dump many
inches of rain very quickly.
Hurricanes develop in the
Atlantic Ocean from tropical
storms. Once a tropical
storm’s wind speed reaches
75mph, it is considered a
hurricane. Hurricanes are
classified into 5 categories
depending on wind their
pressure, wind speed, and
storm surge.
Hurricanes
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Hurricanes
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Quiz
Question 1
The Sun heats the Earth
through…
A)
B)
C)
D)
Conduction
Subjection
Convection
Radiation
Correct!
The Sun heats the Earth
through using the
method of radiation.
Next Question
Incorrect
The Sun heats the Earth
through the method of
radiation.
Next Question
Question 2
Why does an object
travelling due North in
the Northern
Hemisphere get
deflected to the right of
it’s intended path?
A)
B)
C)
D)
Bernoulli’s Principle
Centrifugal Force
Coriolis Effect
Beaufort’s Theorem
Correct!
The object is deflected
due to the Coriolis
Effect.
Next Question
Incorrect
The object is deflected
because of the Coriolis
Effect.
Next Question
Question 3
Water’s boiling point on
the Fahrenheit
temperature scale is…
A)
B)
C)
D)
212°F
100°F
121°F
-460°F
Correct!
Water boils at 212°F.
Next Question
Incorrect
Water boils at 212°F
Next Question
Question 4
The total energy of
motion of all the
molecules in a
substance is called…
A)
B)
C)
D)
Relative Humidity
Heat
Dew Point
Temperature
Correct!
The total energy of
motion of all the
molecules in a
substance is heat.
Next Question
Incorrect
The total energy of
motion of all the
molecules in a
substance is called heat.
Next Question
Question 5
A)
What are the three B)
basic cloud forms? C)
D)
Cumulus, Stratus, Cirrus
Altocumulus, Cirrostratus, Cirrus
Cumulonimbus, Stratus, Cirrus
Nimbostratus, Cirrocumulus, Cirrostratus
Correct!
The three basic cloud
forms are Cumulus,
Stratus, and Cirrus.
Next Question
Incorrect
The three basic cloud
forms are Cumulus,
Stratus, and Cirrus.
Next Question
Question 6
The temperature at
which air becomes
saturated is what?
A)
B)
C)
D)
Relative Humidity
Boiling Point
Dew Point
Absolute Zero
Correct!
The point at which air
becomes saturated is
it’s dew point.
Next Question
Incorrect
The point at which air
becomes saturated is
it’s dew point.
Next Question
Question 7
A huge body of air,
usually 1,000 miles
across or more and
sharing the same basic
characteristics is…
A)
B)
C)
D)
Tropical Depression
Hurricane
Occluded Front
Air Mass
Correct!
A huge body of air,
usually 1,000 miles or
more across and
sharing the same basic
characteristics is an air
mass.
Next Question
Incorrect
A huge body of air,
usually 1,000 miles or
more across and
sharing the same basic
characteristics is called
an air mass.
Next Question
Question 8
A)
The three stages of a B)
thunderstorm are:
C)
D)
Building, Mature, Dissipating
Rain, Thunder, Lightning
Calm, Developing, Violent
Nimbus, Stratus, Cirrus
Correct!
The three stages of
thunderstorm
development are
building, mature, and
dissipating.
Credits
Contents
Incorrect
The three stages of
thunderstorm
development are
building, mature, and
dissipating.
Credits
Contents
Credits
• Created by Ryan Stanley
• Based on Aerospace Dimensions Module 3:
Air Environment
Contents