Hazards Flashcards
What is wind shear defined as?
A change in wind velocity.
May also associated with a change in direction of wind through a level
What is a low level jet?
A fast moving stream of air at low level
What is turbulence?
Irregular and instantaneous motions of air made up of small eddies that travel in general air flow
What is convective turbulence and where is it found?
Caused by rising air currents such as found IN and BELOW cumulus and cumulonimbus cloud
- particularly hazardous shear in Cb’s found between boundaries of updraft and down drafts.
What is mechanical turbulence and where is it found?
Generated by wind blowing over and around surface obstructions.
Severity depends on wind speed and type of surface obstacles (height/roughness) and stability of atmosphere.
Is LEE TURBULENCE found in stable or unstable conditions?
Stable conditions
Mountain waves are an example of lee turbulence in rotor cloud.
What is FRONTAL TURBULENCE?
Wind shear between two masses of air with different density
What is a microburst?
Where is it found?
How long does it last?
Strong concentrated downbursts of air from the base of convective cloud
Squall lines and thunderstorms and virga
Typically lasts for 15 mins
In which cloud type is clear ice most likely in flight above the freezing level
A. Cumulus
B. Nimbostratus
C. Altostratus
D. Altocumulus
B. Nimbostratus
The process involved in the formation of hoar frost is
A. Liquid water freezing on impact with aircraft surfaces
B. Accumulation of ice crystals suspended in the atmosphere
C. Freezing of large super cooled water droplets
D. Deposition of ice directly from water vapour mixed with the air
D. Deposition of ice directly from water vapour mixed with the air
The most likely cause of turbulence over land on a hot day is
A. Thermal activities
B. Mechanical friction
C. Wind shear
D. Temperature inversion
A. Thermal activities
The onset of light wind beneath a radiation inversion will cause the inversion to become
A. Stronger but deeper
B. Stronger but more shallow
C. Weaker but deeper
D. Weaker but more shallow
C. Weaker but deeper
There is little vertical development in cloud within the south east trade winds because of
A. An absence in condensation nuclei
B. An absence in water vapour
C. The pressure of the trade wind inversion
D. The fact warmer air can hold more water vapour
C. The pressure of the trade wind inversion
The pressure system which gives rise to subsidence inversions is
A. Cyclone
B. Anticyclone
C. Col
D. Trough
B. Anticyclone
