Transcript Weather

Weather and meteorology
1LT Jan Kalvoda
22nd Náměšť AFB
Meteorology × Weather
Meteorology – theory about wheather
Weather – current conditions of atmosfere
Meteorology
Atmospheric
phenomena
Meteorogical
elements
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Temperature
Precipitation
Wind (speed, direction)
Humidity
Sunshine duration
Snow cover
Cloudiness
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Rain
Hail
Fog
Rainbow
Halo phenomenon
Lightning
Aurora
Pressure areas
• Depression - An area of low atmospheric pressure
• Anticyclone - An area of high pressure
• Ridge - A line of high pressure extending from an
anticyclone
• Trough - A long area of low pressure running out of
a depression.
• Isobar - A line on a synoptic chart joining points of
equal pressure.
Wind
 movement of gases on a large scale
 Wind is caused by differences in the atmospheric
pressure.
 When a difference in atmospheric pressure exists,
air moves from the higher to the lower pressure
area, resulting in winds of various speeds.
 Long-duration winds have various names associated
with their average strength, such as breeze, gale,
storm, and hurricane.
Fronts and frontal systems
Cold front - The boundary between 2 air masses
where cold air is overtaking warm air. Air
temperature drops and atmosferic pressure
grows.
Fronts and frontal systems
• Warm front - The ground level boundary
between warm air and cold ahead of it. Warm
air force out cold air and extensive cloudiness
risen.
Fronts and frontal systems
• Occluded front - The boundary when a warm and
cold front meet and the warm air is forced up above
ground level.
Clouds
Cloud cover
The amount of cloud which can be seen in the sky
Expression
Cloud cover
Sky clear (SKC)
No clouds
Few (FEW)
1-2 oktas
Scaterred (SCT)
3 – 4 oktas
Broken (BKN)
5 – 7 oktas
Overcast (OVC)
8 oktas
Colour codes
Surface visibility
Cloudbase
(5 oktas or
more)
Colour code
8 km
2500 ft
Blue
5 km
1500 ft
White
3,7 km
700 ft
Green
1,6 km
300 ft
Yellow
0,8 km
200 ft
Amber
Less than 0,8 km
Below 200 ft
Red
The visibility and cloud may be good but the airfield
cannot be used for some other reason (the runway
may be blocked for example).
Black
VMC/IMC
• VMC – visibility more than 5 km, min.
cloudbase 1500 ft (in case of 5/8 or more).
• IMC – any conditions worse than VMC.
Meteorological conditions for SVFR
Minimum ground and flight visibility 1500m,
for rotar wings, aircraft 800m only.
Permanent visual contact with ground
Minimum cloudbase 600ft/180m AGL.
Out of clouds
(Minimum flight hight 500ft/150m AGL)
Meteorological Causes of instrument
meteorological Conditions
Fog (radiation fog, advection fog)
Precipitation (snow, heavy rain)
Low Clouds (lifting, cooling)
High surface Relative Humidity (RH) common
factor in all causes of IMC
Precipitation – Water in any form, liquid
or frozen falling from the sky
Snow
SN
Rain
Drizzle
Hail
Ice pellets
RA
DZ
GR
PL
Snow grains
Sleet
SG
Precipitation (e.g., rain, snow, hail):
- light
- moderate
- heavy
Words associated with precipitation
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Intermittent
Continuous
shower
Flurry
Blizzard
Isolated/ Ocassional
Scattered
Frequent
Widespread
Freezing
Super cooled
Aviation weather
hazards
Freezing level × Icing
The freezing level, or 0°C (zero degree)
isotherm represents the altitude in which the
temperature is at 0°C (the freezing point
of water) in a free atmosphere.
 icing conditions are those atmospheric
conditions that can lead to the formation of
water ice on the surfaces of an aircraft.
Fog
• It is a visible mass consisting of cloud water
droplets or ice crystals suspended in the air at or
near the Earth's surface. Fog can be considered a
type of low-lying cloud.
• Generally reported when vis <5km and there is
no precipitation reducing visibility
• Types: radiation, ground, advection,
evaporation, steam, ice, freezing, upslope fog.
Mist
• Mist (BR) is a phenomenon caused by small droplets
of water suspended in air.
• It is most commonly seen where warm, moist air
meets sudden cooling
• The only difference between mist and fog is visibility.
SQUALL
• A squall is a sudden, sharp increase in wind
speed that is usually associated with active
weather, such as rain showers, thunderstorms,
or heavy snow.
Turbulence
• “Bumpiness” in flight
• Four types
– Low-level turbulence (LLT)
– Turbulence near thunderstorms (TNT)
– Clear-air turbulence (CAT)
– Mountain wave turbulence (MWT)
• Measured as
– Light, moderate or severe
– vertical gust
Thunderstorms
 is a type of storm characterized by the
presence of lightning and its acoustic effect on
the Earth's atmosphere known as a thunder.
Thunderstorms occur in association with a
type of cloud known as a cumulonimbus. They
are usually accompanied by strong
winds, heavy rain and
sometimes snow, sleet, hail…
Dry microbursts from high based
thunderstorms
• When precipitation falls through unsaturated air,
evaporative cooling may produce dry microbursts
• Result in very hazardous shear conditions
• Visual clue: fallstrips (fall streaks that don’t reach the
ground)
Flight
path of
plane
45 kt
downburst
45 kt
headwind
45 kt
tailwind
Weather reports
Name of report
Content
Field of action
Issuer
Form
METAR
Regular report
(every 1 hour)
Actual weather at
airport
Airport
In code
METREPORT
Local regular
weather report
Actual weather
Airport
Spoken
words
SPECI
Exceptional weather
report
Actual weather
Airport
In code
TREND
Landing forecast
Prediction for 2
hours ahead
Airport
In code
TAF
Aerodrome forecast
Prediction for 9/24
hours ahead
Airport/
Area
service
In code
GAMET
Area forecast for
low level flights
Prediction for 5-6
hours ahead
Area
service
In code
AIRMET
Information about
phenomena missing
in GAMET
Warning
Area
service
In code
Name of
report
Content
Field of
action
Issuer
Form
SIGMET
Information about
hazardous phenomena
Actual
weather and
warning
Area service
In code
AD WRNG
Information about
hazardous phenomena
Actual
weather and
warning
Airport
In code
VOLMET
Radio broadcasting for
aircraft in air
All
Big airports
In code
ATIS
Radio broadcasting for
aircraft in air TMA
Actual
weather and
warning
Airport
In code
AIREP
Weather report from
aircraft in the air
Actual wethar
Aicraft in air
In code
• Thank you for your attention…
Questions??
Sources
• Aviation phraseology and terminology for
procedures for navigation services
• Air operational English course
• Wikipedia