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Clear Air Turbulence (CAT) Encounter

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Clear Air Turbulence (CAT) Encounter

1- General
World Area Forecast Centers (WAFC) London and Washington are providing the most accurate information to users: Significant Weather Charts (SIGWX) for high and medium levels, upper wind and temperature charts are provided.

2- Clear Air Turbulence Phenomenon
Clear Air Turbulence (CAT) layers are found along front lines and their jet streams. These areas of vertical exchange of air mass are the most dynamic and significant where two tropopauses overlap each other. When turbulence becomes excessive, an altitude change is more efficient than a track change.

3- Forecast Presentation
The forecast of Clear Air Turbulence (CAT) areas (dashed lines) on SIGWX provide no information of light turbulence. It is a fact that temporary change of a certain level has the greatest influence on the development of CAT.

4- Convective Induced Turbulences
Due to heat radiation from different ground states, e.g. forests, lakes, rocks, RWYs etc. Climb out and approach phase can be uncomfortable.

5- Topographically induced Turbulence
In strong wind conditions behind hills, buildings, etc. These conditions may also cause wind shear.

6- Wake Turbulence
Behind aircraft consists of two counter-rotating cylindrical vortices. The pressure differential between the upper and the lower side of the wing triggers the roll up of the airflow aft of the wing, resulting in swirling air masses trailing downstream of the wing tips. Pilots should avoid a region within less than 200ft of the vortex core. When flying on track systems in oceanic or remote areas offset procedures (i.e. SLOP) may be applied.

Source: ICAO

See also:
Downdraft and Microburst (MB)
Mountain Waves (MTW)
Thunderstorms, CB / TCU
Turbulence Grade Classification
Clear Air Turbulence (CAT) Encounter
Wind Shear

The presented material is for training purpose only!