Transcript Chapter 9
Chapter 9
Meteorology
Section A, Weather Factors
Atmosphere
Comprised of:
• Oxygen - 21%
• Nitrogen - 78%
• Other gases - 1%
99.9% of Atmosphere is within 30 miles
Section A, Weather Factors
Atmosphere is classified by thermal
characteristics
Troposphere
• Lowest level
• contains most weather
• varies in altitude from 24,000’ to 50,000’ with about
36,000’ to 37,000’ in mid-latitudes
• characterized by a decrease in temp with increase in
altitude
Section A, Weather Factors
Tropopause
• above troposphere
• characterized by an abrupt change in temp lapse rate
• About 36,000
Stratosphere
• Severe thunderstorms may extend
• Tops about 160,000’
Section A, Weather Factors
Atmospheric circulation
Weather changes are caused by uneven heating
Every process of weather is the result of or is
accompanied by a heat exchange
The sun is directly over the Tropic of Cancer
on June 21
Section A, Weather Factors
Pressure and wind patterns
Pressure
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Highs - Center of high pressure, peak of hill
Lows - Center of low pressure, bowl
Cols - area between 2 highs, or lows
Ridges - elongated area of high pressure
Troughs - elongated area of low pressure
Section A, Weather Factors
Highs are usually associated with
Good visibility
Light winds
Few clouds
Good weather
Characterized by descending air
Section A, Weather Factors
Lows are usually associated with
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•
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precipitation
cloudiness
poor visibility
bad weather
turbulence
Wind
characterized by rising air
Example of lows are hurricanes and tornadoes
Section A, Weather Factors
Air tries to flow from high to low
At higher altitudes, Coriolis force makes the
wind flow parallel with isobars
At lower altitudes, surface friction weakens
Coriolis force and flows across the isobars
This airflow is wind
Section A, Weather Factors
In the northern hemisphere
Air flows counterclockwise around a low
(cyclonic)
Air flows clockwise around a high
(anticyclonic)
If one were to fly directly to the center of a low,
the winds would come from the left and get
stronger as one got closer
Section A, Weather Factors
Local wind patterns
Unequal heating of land and water
• Land and sea breezes
Mountain and Valley breezes
• On a larger scale these are Katabatic winds.
Section A, Weather Factors
Water
Solid - ice
Liquid - water
Gas - water vapor
• Odorless
• Colorless
Changes states by:
• Evaporation, Sublimation, Condensation,
Deposition, Freezing and Melting
Section A, Weather Factors
Relative Humidity
Measure of how much moisture is present for a
a parcel of air at a temperature.
If a parcel of air has a RH of 100%, it is
saturated. The temperature that it is at is called
the dewpoint. If this parcel were cooled more,
water vapor would clouds, fog, dew or frost
Section A, Weather Factors
Precipitation - condensation nuclei
Drizzle
Rain
Snow
Ice pellets
Hail
Ice crystals
Section A, Weather Factors
For a heavy rain to occur, clouds must be at
least 4000’ thick.
Virga
Wet snow
Ice Pellets
Section A, Weather Factors
Stability
Dry adiabatic lapse rate
Saturated adiabatic lapse rate
Condensation Level
Temperature dew point spread by 4.4F or 2.5C
Condensation nuclei
nimbus
Section A, Weather Factors
Families of clouds
Low
Middle
High
Extensive vertical development
Section A, Weather Factors
Airmass
Continental
Maritime
Polar
Tropical
Section A, Weather Factors
Fronts
Cold
Warm
Stationary
Occluded
301.
I21
COM
Every physical process of
weather is accompanied by or
is the result of
A.
a pressure differential.
B.
a heat exchange.
C.
the movement of air.
301.
I21
COM
Every physical process of
weather is accompanied by or
is the result of
B.
a heat exchange.
302.
I21
What is the standard
temperature at 10,000
feet?
A.
+5 °C.
B.
-5 °C.
C.
-15 °C.
COM
302.
I21
COM
What is the standard
temperature at 10,000
feet?
B.
-5 °C.
304.
I22
COM
What are the standard
temperature and pressure
values for sea level?
A.
15 °C and 29.92" Hg.
B.
15 °C and 29.92 Mb.
C.
Hg.
59 °F and 1013.2"
304.
I22
COM
What are the standard
temperature and pressure
values for sea level?
A.
15 °C and 29.92" Hg.
306.
I23
COM
What causes wind?
A.
Pressure differences.
B.
Air mass modification
C.
The Earth's rotation.
306.
I23
COM
What causes wind?
A.
Pressure differences.
307.
I23
COM
In the Northern Hemisphere,
the wind is deflected to the
A.
left by Coriolis force.
B.
right by Coriolis
force.
C.
right by surface
friction.
307.
I23
COM
In the Northern Hemisphere,
the wind is deflected to the
B.
right by Coriolis
force.
308.
I23
COM
Why does the wind have a tendency to flow
parallel to the isobars above the
friction level?
A.Friction of the air with the Earth
deflects the air perpendicular to the
pressure gradient.
B. Coriolis force acts perpendicular to a
line connecting the highs and lows.
C.Coriolis force tends to counterbalance
the horizontal pressure gradient.
308.
I23
COM
Why does the wind have a tendency to flow
parallel to the isobars above the
friction level?
C.Coriolis force tends to counterbalance
the horizontal pressure gradient.
309.
COM
I23
The wind system associated with a
low-pressure area in the Northern
Hemisphere is
A.
a cyclone and is caused by
Coriolis force.
B.
an anticyclone and is caused by
Coriolis force.
C.
an anticyclone and is caused by
descending cold air.
309.
COM
I23
The wind system associated with a
low-pressure area in the Northern
Hemisphere is
A.
a cyclone and is caused by
Coriolis force.
312.
I23
COM
While flying cross-country, in the
Northern Hemisphere, you experience a
continuous left crosswind which is
associated with a major wind system. This
indicates that you
A.
cannot determine weather conditions
without knowing pressure changes.
B.
are flying toward an area of
generally unfavorable weather conditions.
C.
have flown from an area of
unfavorable weather conditions.
312.
I23
COM
While flying cross-country, in the
Northern Hemisphere, you experience a
continuous left crosswind which is
associated with a major wind system. This
indicates that you
B.
are flying toward an area of
generally unfavorable weather conditions.
313.
I23
COM
Which is true with respect to a
high- or low-pressure system?
A.
A high-pressure area or ridge
is an area of descending air.
B.
A low-pressure area or trough
is an area of descending air.
C.
A high-pressure area or ridge
is an area of rising air.
313.
I23
COM
Which is true with respect to a
high- or low-pressure system?
A.
A high-pressure area or ridge
is an area of descending air.
314.
I23
COM
When flying into a lowpressure area in the Northern
Hemisphere, the wind direction
and velocity will be from the
A.
left and decreasing.
B.
left and increasing.
C.
right and decreasing.
314.
I23
COM
When flying into a lowpressure area in the Northern
Hemisphere, the wind direction
and velocity will be from the
B.
left and increasing.
317.
I24
COM
Moisture is added to a parcel
of air by
A.evaporation and sublimation
B.sublimation and
condensation
C.evaporation and
condensation
317.
I24
COM
Moisture is added to a parcel
of air by
A.evaporation and sublimation
325.
I25
COM
What are the characteristics of
stable air?
A.
Good visibility; steady
precipitation; stratus clouds.
B.
Poor visibility; steady
precipitation; stratus clouds.
C.
Poor visibility; intermittent
precipitation; cumulus clouds.
325.
I25
COM
What are the characteristics of
stable air?
B.
Poor visibility; steady
precipitation; stratus clouds.