Fronts and Masses

Air Masses• The changing of weather

may not have a set pattern, but our forecasts have gotten better over the years

• An air mass is a large body of air that is characterized by temperature and moisture

• This creates and defines our weather.

Air Masses• What an air mass forms (source

region) will determine its characteristics

• Two main characteristics define and Air Mass 1. Moisture content – Forms over land dry air →

Designated the name continental

– Over water wet air/humid → Designated the name maritime

2. Temperature– Forms in colder air →

Designated the name Polar– In warmer/hot air → Designated

the name Tropical

Air MassesThe abbreviation of the air mass must

have a first name that refers to the moisture content and a second that refers to the temperature:

• cP continental Polar – Canada & Alaska)– dry & cold

• cT continental Tropical – Mexico & Florida– dry and warm

• mP maritime Polar – N Atlantic Ocean– Wet and cold

• mT maritime Tropical – Gulf of Mexico– wet and warm

Fronts• When two different air

masses meet different weather event will occur

• A front is the boundary between two air masses that forms clouds and precipitation.

• There are four types:– Cold Fronts– Warm Fronts– Occluded Fronts– Stationary Fronts

FrontsCold Front• Forms when cold, dense air

moves into a region previously occupied by warm air

• Symbol →• Leads to strong winds and

precipitation • Cumulonimbus clouds are

associated with this type of front.

• Usually accompanied by decrease in temperatures

FrontsWarm Front• Forms when warm air

moves into an area formerly covered by cooler air

• Symbol →• Usually moderate to light

precipitation for an extended period of time.

• Causes an increase in temperatures

FrontsStationary Front• Forms when the flow of air is

moving neither towards a cold air mass or a warm air mass, but remains parallel to both

• Symbol →• Little to no precipitation is

associated with this front

FrontsOccluded Front• When an active cold front

overtakes a warm front, an occluded front forms

• Symbol →• Initially, there will be a lot of

precipitation at the beginning of this type of front, but it tapers off to light precipitation.