causes of turbulence and stability of the air

Turbulence is one of the weather phenomena associated with stratiform clouds

False

What is the definition of turbulence?

Irregular motion of air from eddies or vertical currents

Turbulence is more commonly associated with ___ fronts but may also be present to a lesser degree in ____ fronts.

cold, warm

What is the difference between stable and unstable air?

Stable air resists displacement, tending to return to its original horizontal level, while unstable air continues to rise on its own.

What are the 4 main causes of turbulence?

Convective/thermal currents, mechanical turbulence, wind shear, and wake turbulence

Convective (or thermal) currents refer to ______ resulting from air moving ______ in convective currents.

disturbed airflow, vertically

Mechanical turbulence refers to disturbed airflow resulting from air moving _______, such as irregular terrain.

past or over obstructions

Wind shear is a drastic change in _____, _____, or both over a relatively short distance.

wind speed, direction

Wake turbulence is the turbulent air _____ an aircraft that occurs due to the movement of the aircraft, including _______.

behind, wingtip vortices

Only one cause of turbulence may be present at a time.

False

What are the 2 categories of turbulence?

Friction and Thermal

Friction turbulence is caused by the ______ of the movement of wind.

restriction

Thermal turbulence is caused by a _____ in the atmosphere.

rapid temperature change

Name the 3 different types of friction turbulence.

Mechanical, shear, and frontal

Mechanical turbulence is the result of friction between ___ and ____, which causes ____.

the air, ground, eddies

The intensity of the eddy motion depends on:

the strength of the surface wind, the nature of the surface, and the stability of the air

What is the visual indication of mechanical turbulence?

When loose material is blown around, such as sand or snow.

Unstable air will cause loose material to be blown around ______, like ______.

around enough to restrict visibility, blowing snow

Frontal turbulence is the result of ____ between 2 opposing air masses _____.

friction, near the frontal surface

What are the two types of thermal turbulence?

daytime convection, cold air advection

Daytime convection turbulence is the result of _____ caused by ________ of the Earth’s surface.

vertical currents, unequal heating

The strength, extent, and distribution of convection currents are affected by:

Stability of the air, degree of difference in unequal heating, and variations in heating throughout the day and seasons

What time of day and season is daytime convection turbulence most pronounced?

In the afternoon, and in the summer

Cold air advection turbulence occurs when cold air moves over _____ water or land, and _____ from below creates unstable conditions that favour convection currents and turbulence.

warmer, heating

The ____ the contrast between the air and surface temperature, the ____ heat is generated, leading to ____ turbulence.

stronger, more, stronger

What is the approximate cooling rate of a rising water vapour molecule?

1.98°C

What are signs of stable air?

Stratus-type cloud or fog, steady precipitation, consistent, steady winds, low visibility when contaminants are present

What are signs of unstable air?

Cumuliform clouds, good visibility, gusty wind, showery precipitation, thunderstorms

Why does stable air resist vertical motion?

Because the lifted air becomes colder and denser than the surrounding air and therefore sinks.

Why is flying through unstable air bumpy?

If warm air is lifted and becomes surrounded by colder air, it will continue to rise. The colder air aloft will descend, causing up and down movement in the atmosphere.