Weather and climate exam 2

Air changes temperature because____

Pressure changes with height

Air Parcel

imaginary volume of air that we use to model how the atmosphere works

Air cannot ___ nor ___ the air parcel

Escape, enter

Diabatic

A process in which energy is added or removed from the air parcel.

Adiabatic

“Not diabatic.” no energy exchange, temperature change through expansion or contraction

Higher atmospheric pressure at/in the ____

Surface

Rising air parcels….

Expand and cool

Sinking air parcels

contract and warm

The speed of tempurature change is called the

Lapse rate

DALR

Dry adiabatic lapse rate- 10 degrees C per km

DALR is used for _______ air parcels

Unsaturated

SALR

Saturated Adiabatic Lapse Rate- between 5 and 9 degrees C

SALR is used for _______air parcels

saturated

Air Parcels Cool More Slowly if Saturation Occurs

Because latent heat is being released due to condensation, which offsets cooling

ELR

Environmental Lapse Rate- Temperature outside air parcel

ELR is used to calculate

Atmospheric stability

Stable Atmosphere

When displaced, air parcels return to their initial position. ELR < SALR

Unstable Atmosphere

When displaced, air parcels continue to move (even accelerate) in that direction. ELR > DALRUns

Conditionally Unstable

Air parcels are stable when not saturated, unstable when they are saturated. SALR < ELR < DALR

Condensation Nuclei

tiny solid, microscopic particles that water vapor condense onto to form cloud droplets. They can be dust, sea salt, or pollutants

2 ways rain forms

Collision-Coalescense, Bergeron

Collision coalescense

Larger drops fall faster than smaller drops, drops collide, coalesce, form a larger drop, and fall

Collector Drop

Large droplet that falls faster and collects smaller droplets

Bergeron Process

Ice crystal growth at expense of supercooled water droplets

factors influencing collision coalescense

More moisture, Different droplet sizes, Strong updrafts, Electrical charge