Part 3 — Stability, Clouds & Precipitation

What characterizes an absolutely stable atmosphere?

A displaced parcel tends to return to its original position.

What characterizes an absolutely unstable atmosphere?

A displaced parcel continues moving away from its original position.

What characterizes a conditionally unstable atmosphere?

Unsaturated air is stable, but saturated air can be unstable.

What environmental lapse rate indicates absolute instability?

ELR greater than the dry adiabatic lapse rate.

What environmental lapse rate indicates absolute stability?

ELR less than the saturated adiabatic lapse rate.

What ELR range indicates conditional instability?

Between the saturated and dry adiabatic lapse rates.

What happens when ELR equals the dry adiabatic lapse rate?

The atmosphere is neutrally stable for unsaturated parcels.

What is a temperature inversion?

A layer where temperature increases with altitude instead of decreasing.

How does a temperature inversion affect atmospheric stability?

It creates very stable conditions and suppresses vertical mixing.

Why does subsidence inhibit cloud formation?

Sinking air compresses and warms, lowering relative humidity and discouraging condensation.

Why does convection encourage cloud formation?

Rising warm air expands, cools, and may reach saturation.

What are atmospheric gravity waves?

Oscillations that occur when displaced air is pulled back by gravity and buoyancy.

How can mountain waves create clouds?

Air oscillates vertically; rising portions cool and may form clouds.

What are lenticular clouds associated with?

Standing mountain waves and airflow over elevated terrain.

What does cirro- indicate in cloud names?

High-level clouds.

What does alto- indicate in cloud names?

Middle-level clouds.

What does stratus indicate?

Layered or sheet-like clouds.

What does cumulus indicate?

Heap-like or puffy clouds.

What does nimbus indicate?

Rain-producing or precipitation-bearing clouds.

What is a solid middle-level cloud deck called?

Altostratus.