Aviation Weather: Weather Charts Flashcards
What is Mean Sea Level (MSL)
your true altitude or the average height above standard
sea level
What is Above ground level ( AGL)
the height above the ground over which you are flying
Define SIGMET - Significant Meteorological Information
a weather advisory that
contains information about weather events like thunderstorms and severe
turbulence
Define AIRMET - Airmen’s meteorological information
a weather advisory that contains information about weather events that are potentially unsafe - moderate turblulance -high wind -restricted visibility
Visual Flight Rules (VFR)
basic VFR is defined as an airport having at
least a 1,000 foot ceiling and 3 statute miles of visibility
Instrument flight rules (IFR)
is defined as an airport having less than
a 1,000 ceiling and/or less than 3 statute miles of visibility
What is a the difference between Statue mile and Nautical mile?
Statute mile – legal definition of a mile (5280 feet)
Nautical mile - A unit of length used in sea and air navigation, based on the
length of one minute of arc of a great circle, especially an international and US
unit equal to 1,852 meters (about 6,076 feet)
ASOS
primary surface weather observing system for the U.S. and
the data source for METARs and other aviation weather information
AWOS
a weather reporting system that consists of various sensors and a transmitter to broadcast weather data
What is a cloud ceiling
the altitude at the base of a cloud layer
FAA defines it as height of the lowest layer of clouds of the surface that are either broken or over cast but not thin.
How do you calculate the cloud base?
Find the difference between the surface temperature and the dew point.
Divide result by 4.4 (if F) or 2.5 (if Celsius) am multiply by 1000
((Surface temp- dewpoint )/4.4 )* 1000
Octals- how to figure out cloud coverage
Dive skydome into 8 parts. The observer is in the middle looking up.
number of sections with clouds determines cloud cover. Clear, few, scattered, broken, overcast.
Types of Clouds: Cumulonimbus
What part of atmosphere?
Stretches from low to high altitude/ atmosphere. Big puffy cloud
Types of Clouds: Cirrocumulus
What part of atmosphere?
High altitude/atmosphere.
Types of Clouds: Cirrostratus
What part of atmosphere?
High altitude/ atmosphere
Types of Clouds: Cirrus
What part of atmosphere?
High altitude
Types of Clouds: Altocumulus
What part of atmosphere?
Mid altitude
Types of Clouds: AltoStratus
What part of atmosphere?
Mid altitude
Types of Clouds: Nimbostratus
What part of atmosphere?
Mid and low altitude
Types of Clouds: Cumulus
What part of atmosphere?
Low
Types of Clouds: Stratocumulus
What part of atmosphere?
Low
Types of Clouds: Stratus
What part of atmosphere?
Low
Cumulous Clouds
What are they like?
What kind of weather?
sUAS ranking?
Cumulus clouds are probably the most well-known of the
cloud types
generally form from convection, with air rising vertically into the and condensing
into the puffy, cotton-like clouds
Typically, cumulus clouds are associated with pleasant weather
Good for flying sUAS
Cumulonimbus
What are they like?
What kind of weather?
sUAS ranking?
If updrafts become stronger, cumulus clouds may grow
taller into what we call cumulonimbus clouds
These are the towering clouds (up to 60,000 feet) mainly observed during the summer
months
Can be indicative of developing thunderstorms, including lightning, hail, heavy rain and
even tornadoes
Indicators that it might be time to call it a day; effects of weather from these
clouds can extend many miles from their center
UAS ranking: BAD!
If you see mammatus cloud development you should land your vehicle immediately
and be aware of rapidly changing and severe weather developments
Stratus
What are they like?
What kind of weather?
sUAS ranking?
These clouds form when warm air is lifted over cold air, allowing for
uniform water vapor condensation
Looks like a layer blanketing the sky
Generally associated with wet conditions
Can last for days, bring cool temperatures, persistent rain, drizzle, or even snow
Great for imagery because the diffuse sun’s rays light all things evenly
UAS ranking:
Bad for flying if they are too low: ceiling and VLOS
Bad for flying from wet conditions
Cirrus
What are they like?
What kind of weather?
sUAS ranking?
high, thin and wispy clouds very high up in the atmosphere
made up of tiny ice crystals.
Form out ahead of warm fronts and can be indicative of upcoming precipitation
Also develop as part of outflow from large scale storms including thunderstorm
complexes
Not bad for imagery because they filter sunshine
Can be bad for VLOS
What is Airmass
An air mass is a large body of air
When air masses stay over a an area that has generally uniform temperature
and moisture characteristics from one day to the next the mass takes on those
same characteristics
Air masses form in places like polar regions, tropical regions and dry
deserts and are characterized by their temperature and moisture
content
When an airmass passes over a warmer surface convective currents
form creating unstable air with good visibility, increased turbulence,
cumulus clouds and potentially rain showers
When an airmass passes over a cooler surface convective currents do
not form creating stable air with poor visibility, low stratus clouds, fog
and/or steady precipitation
What is a front?
The boundary air layer between two air masses or two areas of
pressure as they get nearer to one another is a front
Approaching fronts always means a change in the weather is
imminent preceded by changes in wind direction, speed and
temperature
When does a Warm Front occur?
Warm fronts occur when a mass of warm air replaces a body of cooler air
Typically slow moving (10-25 mph) and can take days to approach and move on providing
advanced warning
Brings low ceilings, decreased visibility and
When Does a Cold Front occur?
Occur when cold, dense, stable air replaces and body of warmer air
Typically fast moving, almost twice the speed of a warm front, at 25-30 mph
Bring violent weather
What is a stationary Front?
When the force of two airmasses are equal the boundary remains
stationary
Can influence weather along the boundary for days
Weather generated along a stationary front can be a mixture of both warm and
cold front characteristics
Occluded Front
Occurs when fast moving cold air catches up with slow moving warm air
What are Isobars?
They are lines of constant pressure and the area inside the lines depict areas of equal pressure.
