Weather Flashcards
What are acceptable weather sources to use on the ground?
1-800 weather brief
Aviationweather.gov
Foreflight
FSS
What are acceptable weather services to use while enroute?
Metars
FSS
Atc if able
Atis/asos/awos
NEXRAD
What are the types of weather briefings you can get from 1-800 wxbrief?
Outlook
Standard
Abbreviated
When would you get an outlook weather briefing?
Outlook weather briefings are good if you plan on flying in 6 or more hours.
What is a standard briefing?
A briefing you can get within 6 hours of the flight time. Has all airport, and enroute weather information.
What is an abbreviated briefing?
A briefing updating one you have already gotten.
What is a convective sigmet and how long is it valid for?
Issued for:
•Severe thunderstorms
-sfc winds greater or equal to 50knots
- hail over a 3/4inch diameter
-tornados
•heavy precip covering 40% of 3000 sq miles
•embedded thunderstorms
•severe turbulence
•severe icing
•low level wind shear
Valid for 2 hours
What is a SIGMET and how long is it valid?
•Severe icing
•Severe or extreme turbulence
•dust or sandstorms either visibility less than 3 miles
•volcanic ash
(All not related to thunderstorms)
Valid for 4 hours
What is a AIRMET and there types?
Airmets are usually issued for less severe weather(small GA aircraft’s)
•AIRMET Sierra
•AIRMET Tango
•AIRMET Zulu
Valid for 6 hours
What is a AIRMET Sierra?
-IFR conditions or mountain obstruction
What is a AIRMET Tango
(T in Tango for Turbulence)
-Moderate Turbulence
-Surface winds greater or equal to 30 knots
-Low level wind shear (LLWS)
What is a AIRMET Zulu?
-Moderate icing
-Freezing levels
What is Atmospheric Stability?
The ability to resist vertical movement.
What determines if an atmosphere is stable or unstable?
The lapse rate
-2c for every 1000 feet
If it is greater then this it is unstable because it favors vertical movement.
What are the three main things effecting wind?
-unequal heating of earths surface
-Coriolis effect
-surface friction
How does unequal heating of the earths surface affect wind?
It creates different pressure areas where air wants to move from cool,dense, high pressure areas to warm, less dense, low pressure areas, speed depends on pressure gradient force.
Cool air also moves from the poles to the equator which then warms up and moves back to the poles.
How does the Coriolis effect, effect wind?
Earths rotation moves air to the right in the northern hemisphere and moves air to the left in the southern hemisphere.
Why does wind usually cross isobars at an angle?
Surface friction, that is why there is usually a wind direction change around 2000ft.
What are the different types of fronts?
•warm front
•cold front
•occluded front
•stationary front
What is a warm front? And what weather does it usually bring?
A Warm Front forms when a relatively moist, warm air mass slides up and over a cold air mass.
-stratiform clouds
-drizzle rain
-low ceilings
-poor visibility
What is a cold front? And what weather does it usually bring?
A cold front forms when a cold, dense air mass pushes under a warm, lighter air mass, forcing the warm air to rise.
-Towering Cumulonimbus clouds
-Heavy rain
-Temp drops
What is an occluded front? And what weather does it bring?
An Occluded Front forms when a warm air mass gets caught between two cold air masses.
-strong winds
-heavy precipitation
-form in mature low pressure areas
What is a stationary front and what weather does it bring?
Stationary fronts occur when the forces of two air masses are relatively equal, causing the front not to move.
-cloudy
-steady precipitation
-can often last days
What are the types of Low clouds (below 6000ft)
•Stratus
-layered, stable
•Nimbostratus
-thick, contain moisture
•Stratocumulus
-puffy, stable air is lifted
What are the types of mid level clouds?
•Alto stratus
-flat, can contain icing
•Alto cumulus
-Patchy
-Light turbulence, icing
What are the types of high level clouds?
•Cirrus
-Ice crystals above 36,000
•Cirrostratus
-Thick, No icing
•Cirrocumulus
-cotton, Light turbulence
What are the different types of Thunderstorms (SSEAAL)
Severe
Steady state
Embedded
Airmass
Area thunderstorm
squal Line
What is a severe thunderstorm?
Convective sigmet
-3/4 hail
-50kt wind or greater
What is a steady state thunderstorm?
the mature stage may then become a “steady state” thunderstorm cell in which extreme turbulence and large hail may predominate.
What is an embedded thunderstorm?
A thunderstorm embedded in clouds so it is not visible without radar if in IMC.
What is an Area Thunderstorm?
A thunderstorm 40% of 3000sq miles.
What is an Air mass thunderstorm?
Generally, a thunderstorm not associated with a front or other type of synoptic-scale forcing mechanism.
What is a squal line?
A “squall line” refers to a linearly-oriented zone of convection. Usually in front of a cold front.
What are the cell sizes of a thunderstorm?
Single cell
Multi cell
Super cell
What is a single cell thunderstorm?
Often called “popcorn” convection, single-cell thunderstorms are small, brief, weak storms that grow and die within an hour or so.
What is a multi cell thunderstorm?
A multi-cell storm is a common, garden-variety thunderstorm in which new updrafts form along the leading edge of rain-cooled air.
What is a Super Cell thunderstorm?
Large severe storm occurring in a significant vertically-sheared environment; contains quasi-steady, strongly rotating updraft.
What are the three stages of a thunderstorm?
Cumulus
Mature
Dissipating
What is associated with the cumulus stage of a thunderstorm?
First stage of a thunderstorm usually consisting of strong updrafts.
What is associated with the mature stage of a thunderstorm?
This is the 2nd stage, mature stage starts the moment rain or any visible moisture touches the ground.
What is associated with the dissipating stage of a thunderstorm?
The 3rd and last stage of a thunderstorm. Consists of strong downdrafts as the thunderstorm is dissipating.
How do you calculate the freezing level?
(OAT-32/3.5)
What are the 2 types of icing?
Induction
Structural
What is induction icing?
Icing that occurs around the air intake, or carburetor, if this occurs use carb heat as preferred.
What is structural icing and the 3 kinds?
Structural icing is when ice build up accumulates on any surface of the aircraft.
-clear ice
-rime ice
-mixed ice
What is clear ice?
Clear ice or glaze ice is a heavy coating of glassy ice which forms when flying in areas with high concentration of large supercooled water droplets, such as cumuliform clouds and freezing rain.
What is rime ice?
Rime ice is an opaque, or milky white, deposit of ice that forms when the airplane is flying through filmy/stratiform clouds.
What is mixed ice?
Mixed icing, as the name implies, has the properties of both clear and rime icing. Large and small supercooled droplets coexist.
What type of structural icing is most dangerous and why?
Clear icing is the most dangerous because it is the heaviest, hardest to remove, and changes the shape of the airfoil which could pose a huge hazard to your lift.
What should you do if you encounter any sort of icing?
The first thing you should do is tell ATC what is going on, and request a lower altitude or immediate 180 turn. If they’re unable to give that to you, don’t wait: declare an emergency, tell ATC your intentions, and fly the plane to safer air.
What is the difference between de-ice and anti-ice?
(Anti ice is to prevent ice and de ice is to get rid of ice)
•Anti-icing equipment is turned on before entering icing conditions and is designed to prevent ice from forming. Deicing equipment is designed to remove ice after it begins to accumulate on the airframe.
What are some anti ice equipment?
-Pitot heat
-Carb heat
-Window defroster
What are some de-ice equipment? (5)
•Pneumatic de-icing boots
•Weeping Wings
•Bleed air Heated Surfaces
•Electrically Heated surfaces
•Electro Mechanical
What are Pneumatic De-ice Boots?
Rubber boots along the wing that fill with air periodically to break off any ice on the leading edge.
What are Weeping wings?
De-Ice fluid (TKS fluid) weeps out of small holes on the leading edge running back underneath and above the wings creating protection from ice build up.
What are Bleed Air Heated Surfaces?
As long as your engine is running, the bleed air from the turbine section will be hot enough to prevent ice from forming.
What are Electrically Heated Surfaces for De Icing?
Surfaces like jet windshields use this, surfaces are electrically heated to not allow any ice build up.
What is Electro Mechanical De icing?
Electro-Mechanical Expulsion Deicing, or EMEDS, detects ice via a sensor. When ice starts to accumulate, coils behind the leading edge skin start to vibrate, causing ice to break off.
(Doesn’t modify airfoil so it doesn’t increase stall speed)
What are the types of de icing fluids?(4) And what are they for?
•Type I fluid
- thinnest fluid can be used on any aircraft but have the shortest hold over time.
•Type II and IV fluid
- both of these are thick fluid that have long hold over time and take higher speeds to knock off
•Type III fluid
- these are relatively new and have properties of both I and II they are thicker but will blow off with lower speeds.
What are the different types of Fog? (6)
•Radiation
•Advection
•Steam
•Upslope
•Ice fog
•Precipitation Induced
What is Radiation Fog?
Forms on Clear, Calm, humid nights as the surface cools.
What is advection fog?
Low layer of warm, moist air moves over a cooler surface.
What is Precipitation-Induced Fog?
Firms when warm rain or drizzle falls though a cooler layer close to the surface.
What is Steam Fog?
Cool air Moves over warm water.
What is upslope fog?
Forms when moist stable air is forced up a slope.
What is Ice fog?
Water vapor sublimates directly as ice crystals, below -25F.
What are the different types of Turbulence? (7)
•Low level Turbulence
•Mechanical Turbulence
•Convective Turbulence
•Frontal Turbulence
•Wake Turbulence
•Clear Air Turbulence (CAT)
•Mountain wave Turbulence
What is Low level turbulence?
Below 15,000ft due to surface heating or friction within a few thousand feet of the ground.
What is Mechanical Turbulence?
Turbulence that gets created because of obstacles or terrain that interfere with the wind.
What is Convective Turbulence? (Thermal)
Daytime phenomenon, vertical air currents or thermals that that develop by the heating of the surface.
What is Frontal Turbulence?
Occurs in the narrow zone ahead of a fast moving cold front where updrafts can each 1000ft/min and 30kt winds or more.
What is wake turbulence?
Created by wing tip vortices of other aircraft’s, greatest when the plane is heavy slow and clean.
What is Clear Air Turbulence?
Happens in clear air, above 15,000ft, interaction between layers or associated with the jet stream.
What is Mountain Wave turbulence?
Downslope winds can create rotor clouds and be very bumpy from tumbling winds.
What is wind shear?
Sudden drastic shift in wind speed or direction, can happen at any altitude.
How does a low pressure system move?
Up, counterclockwise, in
What weather is associated with a low pressure system?
Bad weather, usually convective because warm air is being pushed up.
How does a high pressure system move?
Down, clockwise, out
What weather is associated with a high pressure system?
Usually good weather, down drafts dissipate any convective weather.
What is a trough?
A elongated area of low pressure.
What is a ridge?
A elongated area of high pressure.
What does it mean when the isobars are close together?
It means there is a steep pressure gradient and can have high wind speeds.
What do you need for a thunderstorm to form?
Moisture
Lifting force
Unstable air
