Weather and Climate

Orographic Uplift
The upward displacement of air that leads to adiabatic cooling
Frontal Lifting
When a warm air mass flows toward a wedge of cold air it is forced upward.  When a cold air mass flows toward a wedge of warm air it slips under the warm air.
Where air moves together
Localized convection
Area of significant localized uplift often associated with thunderstorms
Static stability
Air’s susceptibility to uplift
Unstable air
Air that experiences an uplift
Stable air
Air that resists uplift
Neutral air
Air that neither resists uplift nor is motivated to rise
Conditionally unstable air

Buoyancy of air changes.


Absolutely stable air

Air parcel cools more than ambient air.


Absolutely unstable air


Air parcel cools less than ambient air.


Environmental Lapse Rate
The change in temperature due to elevation
Dry Adiabatic Lapse Rate
5.5 Degree fahrenheit per 1000 feet or 1 degree celsius per 100 feet
Saturated Adiabatic Lapse Rate
3.3 degree fahrenheit per 1000 feet or .5 degree celsius per 100 feet
Areas where temperature increases with elevation
Cirrus clouds

Thin, white, wispy clouds. ;A high cloud.



Extensive, shallow clouds somewhat transparent to sunlight. ;A high cloud.



High, layered cloud with billows or parallel rolls. High cloud.



Extensive, watery, layered cloud. ;Middle cloud.



Shallow mid level cloud containing patches or rolls. ;Somewhat opaque.



Uniform layer of low cloud ranging from grey to whitish.

Low level.



Low cloud producing light rain. ;Dark skies.



Low level equivalent to altocumulus.



Detached billowy clouds with flat bases and moderate vertical development.

May extend through much of atmosphere.



Clouds with intense vertical development with characteristic anvil shape. Very dark and very tall.


Where a water droplet in a cloud hits another droplet.
Process where colliding water droplets combine
Bergeron Process
Deposition of H20 vapor onto an ice crystal. ;Deposition exceeds sublimation
Where an ice crystal falls through a cloud collides with water droplets that freeze onto an ice crystal which leads to rapid growth of a snowflake
When collision and coalescence occur
Cool clouds
Clouds where the temperature is ; than 0 in lower reaches and ; 0 in the upper reaches
Cold clouds
Clouds where the temperature is ; 0 throughout
Ice crystals that have air bubbles in them
Frozen rain that is bounced between the top and bottom of a cloud ’till it is heavy enough to drop
Terminal velocity of water droplets
Maximum speed a water droplet can attain while falling
Raindrops that fall through < 0 degree air and change from liquid to ice
Freezing rain
Rain that freezes when it hits the ground

Lake effect snow


A late fall/early winter condition where cold air mass moves over a warm body of water and leads to much precipitation

Three cell model


Divides circulation of each hemisphere into three belts
Hadley cell

Heat driven. Rainiest zone.

Responsible for the ITCZ

Ferrel cell
Occurs in mid latitudes.  Driven by air movement where air from subtropics moves toward the sub polar.
Polar cell
Heat driven.  Moves air from poles to sub polar.
Semi permanent cells of low pressure
Aleutian and Icelandic lows
Semi permanent cells of high pressure
Siberian, Hawaiian, Azures high
Polar front
Narrow divide between sub polar air and polar
Polar jet stream
Jet stream caused by steeply sloping pressure gradient near polar air mass
Sub tropical jet stream
Associated with Hadley cell near the equator
Rossby waves
Upper atmosphere westerlies between polar and warm front with meridional fluctuations
Extended area of low pressure
Extended area of high pressure
Zonal winds
Winds that move East to or from West
Meridional winds
Winds that move north or south
Ekman spiral
Effect of wind drag on current starting 45 degrees right from prevailing wind.  As it goes down to 100 meters the current turns right until it is 180 degrees from its’ starting direction
Where an area of water is moved away from the shore and water from below is lifted up to replace the lack of water
A reversal of the dry/wet weather system
Foehn wind
Synoptic-scale winds that flow down mountain slopes, warm by compression, and introduce hot, dry, and clear conditions to adjacent lowlands
Chinook wind
Winds that are warmed by compression and descend eastern slopes of the Rocky Mountains
Santa ana wind
Where a high pressure system pushes air west and down out of the Rockies towards CA
Katabatic wind
Winds warmed by compression as they are pushed down off of a plateau. ;Antarctica has the most prevelant
Sea and land breeze
Breezes caused by the differing temperatures between land and sea. ;Vary diurnally
Valley and mountain breezes
Valley breezes occur during the day and mountain breezes occur at night
El Nino
Warm phase of ENSO
La Nina
Cool phase of ENSO
Pacific Decadal Oscillation
20 – 30 year oscillation between water temperature in Pacific NW and tropics
Source region
Uniform area where air masses develop
Cold front
Steep 1:100 of cold air

Warm front


Shallow frontal system
Stationary front
A front that is not moving

Occluded front


A front where warm air has been forced aloft. ;Much precipitation is found there
Polar front theory
The life and functions of a midlatitude cyclone.

Midlatitude cyclones


Major weather systems. ;Cyclogenesis – formation

Mature cyclones – growth

Dissipation – result of occluded front

A positive or negative rotation of a fluid
Conveyor belt theory
3d modeling describing how warm, cold, and dry conveyor belt energies impact mid latitude cyclones
Discharge of electricity in thunder storm

Air mass thunderstorms


Air masses that lead to thunderstorms only representative of part of the air mass
Severe thunderstorms
Wind speed ; 58 mpg, hail ; 0.75″, and can spawn tornadoes
Intensely powerful storms that contain a single updraft zone
Zones of extremely rapid, rotating winds beneath the base of cumulonimbus clouds
A large rotating vortice that often precedes a tornado
Wall clouds
Thick cloud beneath a rotating thunderstorm, a place where severe weather often develops
Non supercell development of tornadoes
Are caused by large uplift of air during a thunderstorm
Climate anomalies being related to each other over long distance.  ENSO being an example
Narrow bands separating dry air from humid air
Meso Convective Complexes
A type of MCS having an oval or nearly circular shape
Meso Convective Systems
A general clustering of thunderstorms