Chapter 8.6 - Hazardous Weather Flashcards
Name the four main types of hazardous weather which affecting flying?
- Reduced Visibility.
- Turbulence.
- Thunderstorm.
- Icing.
Define Prevailing Visibility?
Measurement of the greatest distance visible.
Visibility is a measure of the transparency of the atmosphere affect by which five meteorological factors?
- Fog/Mist.
- Precipitation.
- Smoke.
- Haze.
- Dust.
The horizontal visibility is what in Fog?
Reduced to 1000m or less.
The horizontal visibility is what in Mist?
Above 1000m.
Name two types of Fog?
- Radiation.
- Advection.
How does Radiation Fog occur?
Radiation fog forms as the land cools at night
How does Advection Fog occur?
Advection fog forms from warm, moist air moving over a cold surface.
Name two ways Fog dissipates?
- Increased Windspeed.
- Warming.
Duststorms general reduce visibility to below how many metres?
1000.
Severe Duststorms can reduce visibility to below how many metres?
200.
Haze will be worst when significant concentrations of pollutants are trapped below an inversion associated with (cyclone/anticyclone)?
Anticyclone.
Define Turbulence?
Irregular motion of the atmosphere in both vertical and horizontal direction.
Turbulence that momentarily causes slight, erratic changes in Altitude and/or Attitude is reported as what?
Light Turbulence.
Turbulence that causes greater changes in Altitude and/or Attitude, as well as variations in indicated Airspeed is reported as what?
Moderate Turbulence.
Turbulence which causes large, abrupt changes in Altitude and/or Attitude, which may cause the Aircraft to be momentarily out of control is reported as what?
Severe Turbulence.
Turbulence which causes the aircraft to be violently tossed about and impossible to control is reported as what?
Extreme Turbulence.
Turbulence without changes in Altitude and/or Attitude is known as what?
Chop.
Name four types of Turbulence?
- Mechanical.
- Wake.
- Thermal.
- Low-Level Windshear.
What causes Mechanical Turbulence?
Wind blowing over obstructions such as irregular terrain, buildings and mountains.
What causes Wake Turbulence?
The production of lift by medium/large Aircrafts.
What causes Thermal Turbulence?
Temperature effects and interaction of different air-masses.
What causes low-level Windshear?
Abrupt wind strength and/or direction at low levels.
Name one major reason why Mountain/Standing Wave Turbulence can be extremely dangerous?
The Turbulence has no visible warning.
Turbulence associated with which type of front is more severe than the other?
Cold Front.
What is the general height of low-level Windshear?
Surface to 3000 feet.
Which component of the wind is Windshear affecting?
Horizontal.
When Windshear involves only a change of speed with changing height it is often called what?
Wind Gradient.
Define Shallow Wind Gradient?
The windspeed changes slowly/small amounts.
Define Steep Wind Gradient?
The windspeed changes quickly/large amounts.
Define Overshoot Shear?
Windshear which overshoots the approach path and/or increasing airspeed.
Define Undershoot Shear?
Windshear which undershoots the approach path and/or decreasing airspeed.
Overshoot Shear is also known as what in terms of wind (2)?
- Increasing Headwind Shear.
- Decreasing Tailwind Shear.
Undershoot Shear is also known as what in terms of wind (2)?
- Decreasing Headwind Shear.
- Increasing Tailwind Shear.
On Takeoff what effect will Overshoot Shear have on an Aircraft (2)?
- Increase in Airspeed.
- Increase in Rate of Climb.
On Approach what effect will Overshoot Shear have on an Aircraft (2)?
- Increasing Airspeed.
- Decrease Rate of Descent.
On Takeoff what effect will Undershoot Shear have on an Aircraft (2)?
- Decrease in Airspeed.
- Decrease in Rate of Climb.
On Approach what effect will Undershoot Shear have on an Aircraft (2)?
- Decreasing Airspeed.
- Increasing Rate of Descent.
Windshear which causes minor variation on an Aircraft’s flight path and/or Airspeed is known as what?
Light Windshear.
Windshear which has a significant effect on the Aircraft control is known as what?
Moderate Windshear.
Windshear which causes a high degree of difficulty in keeping an Aircraft’s flight path and/or Airspeed is known as what?
Strong Windshear.
Windshear which has hazardous effects on an Aircraft’s controls or rapid changes in wind direction/speed is known as what?
Severe Windshear.
The Turbulence Penetration Speed for Light Training Aircraft is describe as what?
Between 40%-60% above the Clean Stall Speed.
Name two types of Icing that affects an Aircraft?
- Structural Icing.
- Induction Icing.
What happens to the aerodynamic characteristics of the Aircraft when ice forms?
Lift is reduced with the Stall Speed and Drag increasing.
Name three factors which Icing has on Aircraft in flight?
- Increase in Weight.
- Increase in Stall Speed.
- Loss of Lift.
Name three factors which determine the rate of Ice accumulation?
- Water.
- Temperature.
- Size of Liquid Drops.
What is the Droplet Size for Clear Ice?
Large.
At what temperatures will Clear Ice form?
0°C – 10°C.
Name three hazards of Clear Ice?
- Rapid Build-up.
- Possible Loss of Control.
- Difficulty in Removing the Ice.
What is the Droplet Size for Rime Ice?
Small.
At what temperatures will Rime Ice form?
0°C – 20°C.
Name two hazards of Rime Ice?
- Loss of Aerodynamic Efficiency.
- Possible Loss of Control.
What is the Droplet Size for Mixed Ice?
Medium.
At what temperatures will Mixed Ice form?
0°C – 15°C.
How does Frost affecting flying (2)?
- Disrupt the Aerodynamic Efficiency.
- Reduce Visibility.
Airframe Icing decreases what (2)?
- Lift.
- Thrust.
Airframe Icing increases what (3)?
- Drag.
- Weight.
- Stall Speed.
True or False. 10mm of icing can reduce the lifting capabilities of up to 50%?
True.
How long does it take for 10mm of Icing to occur on the airframe in severe icing conditions?
1-2 minutes.
What two actions can a Pilot do to avoid Airframe Icing in Stratiform Clouds?
- Descend to a level where Temperature is above 0°C.
- Climb to a level where Temperature is below 20°C.
What action should a Pilot not do to avoid Airframe Icing in Cumuliform Clouds?
Do not climb.
If a Pilot can’t descend out of a Cumuliform Cloud due to low cloud base, what course of action should be taken to avoid Airframe Icing?
Clear the cloud by turning 180°C.
What three factors are required for Cumulonimbus Clouds to produce Thunderstorms?
- Unstable Atmosphere.
- Sufficient Water Vapour.
- Trigger Action (Type of Thunderstorm).
True or False. All Cumulonimbus Clouds produce Thunderstorms?
False.
Name three types of Thunderstorms?
- Frontal.
- Air-mass.
- Orographic.
How are Frontal Thunderstorms formed?
Interaction of two air-masses (cold displacing warm air) at the frontal boundary.
True or False. Air-mass Thunderstorms are associated with a Front?
False. They are generally isolated.
Name three types of Air-mass Thunderstorms?
- Heat.
- Cold-stream.
- Convergence.
How are Heat Thunderstorms formed?
Through Convection by the heating from the ground.
How are Cold-stream Thunderstorms formed?
When moist air is heated from below and becomes unstable.
How are Convergence Thunderstorms formed?
When moist air is forced to raise
How are Orographic Thunderstorms formed?
When wind forces moist, unstable air to rise over high ground.
Name three stages of a Thunderstorm?
- Cumulus.
- Mature.
- Dissipating.
Cumulus Stage of Thunderstorm is dominated by what?
Strong Updrafts.
How long does a Cumulus Stage last for?
15 minutes.
Mature Stage of Thunderstorm is dominated by what?
Strong Updrafts and Downdrafts.
How long does a Mature Stage last for?
20 minutes.
Dissipating Stage of a Thunderstorm is dominated by what?
Strong Downdrafts.
How long does a Dissipating Stage last for?
30 minutes to 1 hours and 30 minutes.
Name four Thunderstorm Hazards?
- Turbulence.
- Hail.
- Icing.
- Lightening.
Where does the worst Turbulence occur in a storm?
Middle and Upper Levels.
True or False. Turbulence doesn’t exist several thousands of feet above and laterally of a storm?
False. It does.
How can a Pilot tell the magnitude of Turbulence on the bottom leading edge of a storm?
By the roll of clouds.
Other than Turbulence, what is the second worst thunderstorm hazard?
Hail.
Where does Hail often appear to fall?
The overhanging ‘anvil’ of the storm.
Where is the best path to avoid the Hail from a Thunderstorm?
Upwind of the cloud.
How can Lightning affect the stand-by magnetic compass?
Induce permanent errors.
A Pilot should avoid severe storms by at least how many miles?
20.
Name two types of Downbursts?
- Microbursts.
- Macrobursts.
What are the three main characteristics of a Microburst (Length, Wind Speed and Duration)?
- 50m to 1km in diameter.
- Wind Strength up to 150 knots.
- Duration between 10-20 minutes.
Name three types of weather conditions where Microbursts can occur?
- Thunderstorms.
- Rain Showers.
- Virga.
What dangers can Microbursts have on an Aircraft?
Low-level Windshear.
The initial outcome of a Microburst will always be an (increase/decrease) in Airspeed caused by the (increase/decrease) in Headwind?
- Increase.
- Increase.
What’s the main difference between an Aircraft entering a symmetrical and an asymmetrical Microburst?
Conditions in Headwind and Tailwind.
