fss 304.3 + 4 - describe lifting processes and atmospheric stability

What are the 5 lifting processes?

Convection, Convergence, Orographic Lift, Mechanical Turbulence, Frontal Lift

Lift can result from the ______ of the Earth’s surface. Air that has been warmed (primarily by conduction) becomes _____ and therefore lighter than the surrounding air and rises to be replaced by sinking cooler air.

uneven heating, less dense

Mechanical turbulence is the result of ________ produced from the interaction between the surface of the earth and the air. This friction may disrupt the lower part of the air flow into _____.

the friction, a series of eddies

The eddies or mixing of air caused by mechanical turbulence will cause the air to rise. Normally, the type of cloud observed during these circumstances is _____.

stratocumulus

The 3 factors that influence the intensity of mechanical turbulence are:

• Unevenness of the ground

• Speed of the wind

• Stability

The effects of mechanical turbulence are usually limited to the lowest _______ of the atmosphere. This is also known as ______.

3,000 feet, the boundary layer

Orographic lift occurs when an air mass is forced from a low elevation to a high elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools ______ until the air reaches _____, creating cloud and possibly precipitation.

adiabatically, saturation

Frontal lift occurs:

• With a cold front, when _______ undermines the warmer air, forcing it _____ or

• With a warm front, when ______ rises above ________

• advancing cold air, upward

• less dense warm air, retreating colder air

Convergence is usually associated with areas of ______. When air accumulates near the surface, excess air is forced to rise.

low pressure (lows and troughs)

At the surface, low pressure systems have ______ in the Northern Hemisphere, with the wind turning slightly inwards towards the lower pressure.

a counter-clockwise rotation

Lift from convection can rise much higher than mechanical turbulence.

Convection provides lift as long as the parcel of air is ______ than the surrounding air.

warmer

The greater the stability of the air, the more the atmosphere will ______.

resist vertical motion

Stability is ________

the atmospheric resistance to vertical motion

A stable lifted parcel of air will _______ after the lifting process or agent has been removed. In this case, the temperature in a parcel of air could be ______ to that of the surrounding air.

return to its original position, lower

A neutral parcel of air will ______ after the lifting process or agent.

In this case, the temperature in a parcel of air could be _____ to that of the surrounding air.

stay in the new position, equal