4 Stability and Storm Development Free Online FlashCards

How does a stable atmosphere respond to a lifted parcel?

A stable lifted parcel becomes cooler and denser than the surrounding air, so it tends to sink back and vertical motion is suppressed.

How quickly does a rising unsaturated parcel cool?

As pressure decreases during ascent, an unsaturated parcel expands and cools at about $9.8\,^{\circ}\mathrm{C}\,\mathrm{km}^{-1}$, the dry adiabatic lapse rate.

What are four common mechanisms that lift air?

Common lifting mechanisms are surface heating and convection, orographic lifting over terrain, frontal lifting, and convergence of surface winds.

How does rising air form cloud particles?

Rising air expands and cools. Once saturated, water vapor condenses onto tiny particles to form cloud droplets; ice crystals may form in cold cloud regions.

What three ingredients typically support thunderstorms?

Thunderstorms typically need moisture, instability, and lift: moisture supplies water, instability allows buoyant air to keep rising, and lift starts the ascent.

What characterizes a thunderstorm’s developing stage?

In the developing stage, an updraft carries warm, moist air upward and the cloud grows, often from cumulus into towering cumulus.

What happens to a lifted parcel in unstable air?

An unstable lifted parcel is warmer and less dense than the surrounding air, so it continues rising and can support vigorous updrafts.

What makes an atmosphere conditionally unstable?

An unsaturated parcel may initially be stable but become buoyant after rising enough to reach saturation. This condition commonly supports thunderstorms.

What happens at the lifting condensation level?

The lifting condensation level (LCL) is the height where a rising parcel becomes saturated and cloud droplets can begin to form.

What is a temperature inversion, and how can it affect rising air?

A temperature inversion is a layer where temperature increases with height. It can act as a cap that limits rising air and suppresses cloud growth.

How does the pace and concentration of ascent affect weather?

Broad, gradual ascent often forms extensive layered clouds and widespread, longer-lasting precipitation; concentrated or rapid ascent can produce towering clouds and showers or thunderstorms.

How does stability influence cloud shape and growth?

Stable air commonly favors flatter, layered clouds. Unstable air encourages vertical growth from small cumulus to towering cumulus and potentially cumulonimbus.