Weather and Climate Test 3 Review

Air Masses

Masses of air characterized by uniform temperature and moisture characteristics

• Form over broad geographical areas (source regions) 

Formation of uniform air masses are generally promoted by

High Pressure Systems

Maritime Air Mass (m)

Moist

Continential Air Mass (c )

Dry

Tropical Air Mass (T) 

Warm 

Polar Air Mass (P)

Cold

Air Mass Geographic Location

• Gulf of Mexico (g)

• Pacific (p)

• Canadian Plains ( c )

• Atlantic (a)

• Sonoran (s)

Dry Line (Squall Line)

A boundary seperating a dry air mass from a moist air mass - narrow band of thunderstorms

• Air behind west is denser which can force moist air to rise, triggering thunderstorms

Nor’Easter

Low pressure, macroscale cyclone that is formed due to interaction of northern cold, dry air and warm, moist air from the Gulf Stream (East)

• Typically occurs along the East Coast of the U.S. 

• Spin counterclockwise in the Northern Hemisphere 

Mid-Latitude Cyclone

A low pressure, counterclockwise cyclone that forms due to the mixture of cold and warm air masses

• forms between 30 and 60 degrees 

• develop along the polar front where the air masses meet

Cold Front

Occurs when a cold air mass overtakes and replaces a warm air mass 

• moves faster than warm fronts 

• steep frontal boundary

• often followed by precipitation 

• cumulonimbus clouds 

Warm Front

Occurs when a warm air mass replaces a cold air mass

• slower than cold fronts

• light precipitation

• less steep

Stationary Front

Occurs when a front shows no movement over a period of hours 

• cold and warm fronts meet but neither are strong enough to move the other 

• stable boundary 

Occluded Front

Occurs when a cold front overtakes a warm front causing the warm air to be lifted and “cut off” between two cold air masses 

• heavy precipitation 

• change in wind direction 

Atmospheric Stability 

Tendency for air partcels to rise vertically, thereby inducing precipitation

• depends on relationship between ELR, DAR, and WAR 

Stable Atmosphere

Air parcel tends to resist vertical movement

• flat, layered clouds

• smooth air

• steady, light precipitation

• low lapse rate

Instable Atmosphere 

conditions lead air particles to rise (buoyancy) due to parcels being warmer than the surrounding environment

• creates vertical development of clouds

• potential for severe weather

There was an _____ in natural catastrophes due to meterological and climatic events

increase 

Death rates from weather related events have ____

decreased

There has been an increase in billion-dollar weather and climate disasters due to _____ 

population increase and population shift to storm-prone coastal states

____ is the state with the most billion dollar disasters due to its large size, huge population, and wide variety of weather events 

Texas 

Thunderstorms

Form from cumulonimbus clouds in a convectively unstable atmosphere

• common in both low and middle latitudes (especially afternoon hours of the warmest months

The most thunderstorm-prone region in the U.S. is the

Gulf Coast

Stages of Thunderstorm Development

Stage 1: Cumulus

Stage 2: Mature

Stage 3: Dissipating

Thunderstorm Stage 1: Cumulus

Vertically growing cumulus clouds

• convecitional uplift of moist, unstable air (updraft)

• air is warmed by latent heat

• cloud contains moisture but very little precipitation

Thunderstorm Stage 2: Mature 

• updrafts and downdrafts

• precipitation, lightening, and thunder occurs 

• lasts minutes to hours

Thunderstorm Stage 3: Dissipating

• moist air supply runs out causing dissipation

• uplift stops and only downdrafts form 

• light rain may occur 

The rate of air flow into the hurricane at its base must be ___  the rate of airflow out of its top

less than 

The ______ is the preferred location for the development of tornadic thunderstorms 

right front quadrant

Hurricane Formation

• forms over warm ocean water (80 degrees or above)

• between 5 and 20 degrees North and South of the Equator

• derives energy from latent heat 

• requires existence of a pre-existing weather disturbance 

• upper level divergence of air is greater than lower level convergence 

Saffir-Simpson Scale

a 1-5 rating system that classifies hurricane intensity based on sustained wind speed and potential damage

• Category 1 being the weakest and Category 5 being the strongest

Eye of a Hurricane

5 - 22 mile diameter region of calm, clear conditions located at the center of the hurricane

Eyewall (collar)

towering wall of cumulonimbus clouds surrounding the eye of a hurricane

• windspeeds here are the greatest 

Stormsurge

An elevated dome of water that develops under a hurricane as a result of low pressure, flow of water towards the eye, and astronomical high tides

Tornado

Intense cyclonic vortexes that emenate from cumulonimbus clouds in contact with cold fronts characterized by intense thunderstorm activity

Approximately 75% of tornadoes travels from _____ along the frontal boundary 

southwest to northeast

Most tornadoes occur in _____ when mTg, mTa, or cPc air masses collide in the mid-lattudes

Spring

Tornado Alley

Warm, moist air from teh Gulf of Mexico clashes with cool, dry air from the Rocky Mountains, and flat open terrian of the Great Plains allows a mix creating violent thunderstorms or supercells

Fujita Intensity Scale

a system for rating tornado intensity based on the damage they caused to human-built structures and vegetation

• tornado gets rated after it hits and damage is done 

Tornado Watch 

Conditions are right for a tornado to develop, although none have yet been detected 

Tornado Warning

A tornado has either been sighted or rotation has been detected on a Dopplar radar