Turbulence Flashcards
What is Convective Turbulence?
The different specific heat capacities of surface materials produces different temperature rises. This will cause different rising currents, known as convective turbulence.
What is Mechanical Turbulence?
Friction between the air and the ground, especially irregular terrain and man-made obstacles, causes eddies and therefore turbulence in the lower levels, known as Mechanical Turbulence. The layer in which this occurs is known as the ‘Friction Layer’.
What effects the degree of Mechanical Turbulence present?
The degree of mechanical turbulence present in the Friction Layer depends upon the strength and stability of the surface wind and the nature of the surface.
What is Wind Shear?
Wind Shear is a rapid change of wind speed and/or direction over a short distance horizontally or vertically.
When is Wind Shear most dangerous to aviation?
When it occurs closest to the ground
When are the situations that a pilot is most likely to encounter wind shear?
Climbing or descending through an inversion
Climbing or descending through a warm front
In the lee of high ground or large buildings
In the vicinity of standing waves
Flying near or underneath cumulonimbus
What is a particularly hazardous form of Wind Shear?
Low Level Wind Shear
Why is Low Level Wind Shear dangerous?
It may cause changes in wind velocity and directiom that occur faster than an aircraft can accelerate or decelerate to compensate for them.
What is a microburst?
A microburst is a column of sinking air (downdraft) within a thunderstorm.
What is LLWSAS?
Low Level Windshead Alert System
How many anemometers does a LLWSAS need?
5
What is the usual diameter of a microburst?
2.5 miles or less
What is Clear Air Turbulence?
CAT
Clear Air Turbulence is turbulence that occurs without any cloud to indicate its presence.
Where does CAT occur?
It can occur anywhere but is normally associated with strong winds in the upper troposphere or lower stratosphere, ie the Jet Stream.
How can pilots detect CAT?
Significant outside air temperature change that will be experienced when flying through the frontal boundary of warm and cold air.
