Turbulence Flashcards
Turbulence
Irregular motion of air resulting from the formation of eddies/ vertical currents in the air
4 main causes of turbulence
- Convective (thermal) currents
- Mechanical turbulence
- Wind shear
- Wake turbulence
Signs of stable air
Stratus type cloud/ fog
Low visibility when dust/ smoke/ fog are present
Steady precipitation
Consistent/ steady wind
IFR conditions for ceiling & visibility
Signs of unstable air
Cumuliform clouds
Good visibility
Gusty wind
Showery precipitation
Thunderstorms
2 categories of turbulence
Friction
Thermal
3 types of turbulence caused by friction
Mechanical turbulence
Shear turbulence
Frontal turbulence
2 types of turbulence initiated by heat
Daytime convection turbulence
Cold air advection turbulence
Intensities of turbulence
Light
Moderate
Severe
What determines the intensities of turbulence
Initiating lifting agent
Degree of stability of the air
Classification of downbursts
Macrobursts
Microbursts
Macroburst
Downburst 4km or more diameter
Last 5 - 20 min
Microburst
Downburst less than 4 km (2.2NM) in diameter
Less than 5 min
Virga
Precipitation falling but not reaching ground
2 types of wind shear
Directional shear
Speed shear
High level wind shear
Turbulence encountered at higher altitudes
Mainly associated with jet streams