Turbulence And Wind Shear

Question 1

Turbulence

Answer 1

Small scale, short term, random and frequent change to velocity of air.
Main types of turbulence are:
Convective
Mechanical
Orographic
Frontal
CAT

Question 2

Wind shear

Answer 2

When wind or direction changes within a shallow layer, this results in wind shear.
Vertical or horizontal wind shear.
Low level wind shear below 1600ft agl.

Question 3

Wind shear inversion

Answer 3

For this to be significant it requires:
Free stream wind speed over 40kts.
Temperature inversion of 10 degrees or more.

Question 4

Wind shear: valley inversion

Answer 4

Katabatic winds can result in a valley inversion forming.
High risk of wind shear at low altitudes.

Question 5

Wind shear : friction layer

Answer 5

High mechanical and thermal turbulence

Question 6

Topographical windshear

Answer 6

Caused by:
Line of trees,
Buildings,
Funnelling,
Mountains

Question 7

Low level wind shear alert system

Answer 7

Measures average surface wind speed and direction using a network of remote sensor stations.
Updated every minute.

Question 8

Categories of turbulence

Answer 8

Occasional - less than 1/3 of the time
Intermittent - 1/3 to 2/3 of the time
Continuous - for than 2/3 of the time

Question 9

Light turbulence

Answer 9

Slight changes in altitude
IAS changes 5-15kts

Question 10

Moderate turbulence

Answer 10

IAS changes 15-25kt (0.5-1g)

Question 11

Severe turbulence

Answer 11

Abrupt large changes in altitude
IAS changes more than 25kts (>1g)

Question 12

Avoiding turbulence

Answer 12

Low altitude- avoid flying in friction layer, fly higher than, and upwind of mountains.

High altitude - avoid climbing, go around.

Question 13

To avoid CAT….

Answer 13

Stay clear of strong, curved jet streams

Question 14

Jet streams have minimum speed of 60kts

Question 15

Windier lower equals downburst etc