Transcript Snímek 1

Meteorology
Lenka Petrášová
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Definitions
• Meteorology
– Study of the atmosphere & the processes that causes
weather
• Weather
– State of the atmosphere at a particular place & time.
Described by T, Humidity, Ppt., Wind speed
• Climate
– Average values of weather conditions at some place for at
least 30 years
• Climatology
– Study of climate, control, spatial and temporal variability
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Climatic Zones
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Atmosphere
• Mixture of gases surrounding the
earth
• Devided into layers
• Troposphere: surface to 36 000 ft
- where most of weather is
-Tropopause- top of troposphere,
jet stream, turbulence, top of
thunderstorms
Stratosphere: to 160 000 feet
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Composition of the atmosphere
• Gases
- Nitrogen 78%
- Oxygen 21%
- Other 1%
- Water vapour 0% - 4%
• Pollutants
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On the Weather Maps
• Isobars- lines which join the points of equal
atm. pressure, identify pressure systems
• Low pressure
• High pressure
• Trough of low
(brázda)
• Ridge of high
(hřeben)
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Fronts
Symbols on map
Boundaries between air masses
•COLD- where cold air is overtaking warm air
•WARM- where warm air is overtaking cold air
•OCCLUDED- when a warm and cold front
meets and the warm air is forced up above
ground level
•STATIONARY- when a warm or cold front
stops moving
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Clouds
• Amount of clouds: Sky cover- sky clear (no
clouds); few (1/8-2/8 cloud cover); scattered
(3/8-4/8); broken clouds (5/8-7/8); overcast
(8/8)
• Gouped into 3 levels:
– Low level: surface to 6500 ft( stratus, cumulus)
– Medium level: 6500- 20 000ft AGL (altostratus,
altocumulus, cumulonimbus)
– High level: above 20 000 ft AGL ( cirrus, cirrostratus)
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Meteorological phenomena
• Precipitation (rain, hail, snow, snow grains, sleet,
flurry, blizzard, whiteout)
• Wind ( windshear, gust, squall, breeze, jet
streams)
• Mist- vizibility more than 1 km
• Fog- vizibility less than 1 km
• Humidity- the amount of water in the air
• Dew point- the temperature to which air must be
cooled before water vapour turns back to water
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Danger for flight
• Turbulence- Turbulence is caused by the
relative movement of disturbed air through
which an aircraft is flying
-arise from strong wind over irregular terrain
or obstacles, air movements associated with
convective activity (thunderstorms and
lightning)
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• CAT- Clear Air Turbulence is defined as
turbulence which is NOT associated with cloud
and therefore cannot be detected visually or
by conventional weather radar.
- caused by flow of air in an
unstable atmosphere
• Source of CAT could be a JET STREAM- high
level wind which is important to navigation
because it blows more than 200 knots ->
reduce fuel consumption
- generated as a result of the temperature
gradient between air masses
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• Icing - Icing conditions exist when the air contains
droplets (kapičky)of supercooled liquid water
- Removal:
a) If there is ice prior to take off on an aircraft:
- Application of deicing fluid
- Use of infrared heating
b) In flight:
- Electrical heating
- pneumatic deicing boots ( inflated rubber which breaks the
ice)
- hot air from compressor
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• METAR- Aerodrome routine meteorological
report
• TAF- Aerodrome forecast
• NOTAM- a notice containing information
concerning the establishment, condition or
change in any aeronautical facility, service or
procedure
• SIGMET- information concerning en- route
weather which may affect the safety of aircraft
operations
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Used sources:
www.skybrary.aero
Keller,Ladislav. Učebnice pilota 2008
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