Chapter 7.2 - An Introduction to Meteorology Flashcards
Name three weather phenomena that have more detrimental effect on an Aircraft at relatively low level?
- Poor Visibility/ Low Cloud Ceilings.
- Thunderstorms.
- Turbulence.
- Windshear.
- Thermals and Dust Devils.
Poor Visibility is associated with what (3)?
- Low Cloud Ceilings.
- Fog/Duststorms/Haze.
- Precipitation.
Name four examples of Precipitation?
- Heavy Rain.
- Drizzle.
- Snow.
- Sleet.
True or False. Clouds are formed when the moist air is cooled to below a temperature where it cannot hold any more water vapour?
True.
When the air is unstable, what type of clouds are formed?
Cumuliform Clouds.
When the air is stable, what type of clouds are formed?
Stratiform Clouds.
Clouds which are bunched or heaped together, have a significant vertical development and are generally separated from each other are called what?
Cumuliform.
Clouds which are formed into sheets or layer, which may cover large areas of the sky are called what?
Stratiform.
Low Cloud is classified as cloud with a base from the earth’s surface up to about ‘x’ feet. What is ‘x’?
8500ft.
A stable atmosphere is normally associated with what kind of pressure area?
High.
High Pressure Area is also known as?
Anticyclone.
Stratus usually has a very low base. What two factors can reduce the visibility in VFR flight?
- Low Ceiling.
- Drizzle.
Fog can reduce horizontal visibility to ‘x’ metres or less. What is ‘x’?
1000m.
In Mist, the horizontal visibility generally remains (above/equal/below) 1000 metres?
Above.
True or False. Stratocumulus can also have a low base, or obscure high terrain?
True.
Name two types of Low Cumuliform Clouds and their abbreviations as used in weather forecasts?
- Cumulonimbus (CB).
- Cumulus (CU).
An unstable atmosphere is normally associated with what kind of pressure area?
Low.
Low Pressure Area is also known as?
Depression.
What is the name given to lines joining places of equal pressure on a weather map called?
Isobars.
True or False. The closer together the Isobars, the lighter the wind?
False. The stronger the wind.
In the Southern Hemisphere, the wind blows anticlockwise around what kind of pressure area?
High Pressure Area (anticyclone).
In the Southern Hemisphere, the wind blows clockwise around what kind of pressure area?
Low Pressure Area (depression).
What does NS stand for?
Nimbostratus.
Temperature Inversion is a condition in the atmosphere where the temperature (increases/decreases) with height?
Increases.
Severe dust storms may reduce visibility to below ‘x’ metres?
200m.
Name seven meteorological hazards that Thunderstorms produce?
- Turbulence.
- Hail.
- Icing.
- Lightening.
- Gusts.
- Low Ceiling.
- Poor Visibility.
What should Pilot if they see a Thunderstorm ahead?
Avoid at all costs.
What is the worst hazard of a Thunderstorm?
Turbulence.
True or False. Turbulence from a Thunderstorm is not enough to cause severe structural damage?
False. Turbulence from a Thunderstorm has the potential to cause structural damage.
True or False. Hailstones from a Thunderstorm can be extremely large and damage an Aircraft?
True.
What can ice deposits on an airframe lead to what degrading performances on an Aircraft (3)?
- Reduction in Lift.
- Increase in Drag.
- Can cause the Aircraft to stall at higher speeds.
Name five possible signs indicating Turbulence in the Air?
- Thunderstorms.
- Towering Cumulus Clouds.
- Strong Winds (in the excess of 25kts).
- Virga.
- Cold Fronts.
Define Virga?
Precipitation which evaporates before reaching the ground.
What does Virga suggest?
Strong downdrafts.
What should Pilots do if they detected presences of Virga?
Avoid flying underneath these clouds.
What is a ‘front’ in weather terms?
Two air masses of differing temperatures (warm and cool).
Define Cold Front?
Cooler air displaces warm air.
How is a Cold Front displayed on a weather map?
A line marked with barbs in the direction of movement.
What does FBL stand for in relation with Turbulence?
Feeble/light.
What does MOD stand for in relation with Turbulence?
Moderate.
What does SEV stand for in relation with Turbulence?
Severe.
Apart from Thunderstorms, can Turbulence itself cause Structural Damage?
Rarely.
The critical factor with Turbulence is the Aircraft’s speed. What can happen at high and low Airspeeds (2)?
- High = Overstress the structure.
- Low = Gust-induced roll.
True or False. A compromise speed must be used to penetrate turbulence if flight through turbulence cannot be avoid?
True.
For Light Training Aircraft, the turbulence penetration speed is between which percentages above the clean stall speed?
40% to 60%.
Where can the turbulence penetration speed be found in?
Pilot’s Operating Handbook.
Unexpected Turbulence: How should the speed be changed?
Slowed down to its turbulence penetration speed.
Unexpected Turbulence: What should be checked in the cockpit?
Any loose articles.
Unexpected Turbulence: What position should the flaps be at?
Up position.
Unexpected Turbulence: What changes should be made with the Attitude?
Small changes.
Unexpected Turbulence: Should a Pilot re-trim the Aircraft?
No.
Unexpected Turbulence: What should be avoided if turning the Aircraft?
Large bank angles.
Low level Windshear is the term used to describe what? From the surface to about ‘x’ feet AGL (2)?
- Sudden change in wind speed and/or direction.
- 2000ft AGL.
When Windshear involves only a change in speed with changing height, this is called what?
Wind Gradient.
Name two signs of that may indicate the presence of Windshear?
- Strong Winds.
- Forecast Gusts.
What are Thermals?
A column of hot rising air.
Which type of flight will Pilots use Thermals?
Gliders as it allows the glider to gain height.
True or False. Dust Devils are smaller and less violent form of Thermals?
False. More violent form of Thermals.
Dust Devils move at speeds varying between how many knots? They normally only rise to height of less than ‘x’ feet (2)?
- 5 to 25 knots.
- 100 feet.
The forecast signs of Thermals and Dust Devils are in which conditions?
Hot and Dry.