Frontal Weather

ByDiana L. Duckworth

Rustburg High SchoolCampbell County, VA

Fronts are the boundaries between air masses.

• Cold Front – cold, dense air pushes out warm air; polar air mass moves south.

• Warm Front – warm, low density air drags cold air out; tropical air mass moves north.

• Stationary Front – air masses stop moving• Occluded Front – cold front overtakes a

warm front and scoops warm air up – front is present only in upper atmosphere.

Cold Air

Warm Air

Sharp drop in air pressure, followed by clearing.

Short, violent storms – Thunder & Lightning Tornadoes High winds, hail Heavy downpours

Cold Front Weather

Vertical development clouds – cumulus & cumulonimbus

Warm Air

Cold Air

Pressure gradually decreases then rises.Slow moving, covers 100’s of miles.

Clouds gradually decrease in altitude; horizontal development.Rain or snow are steady; weather is not violent.

cirrusCirrocumulus, cirrostratus

Altocumulus

Altostratus

Stratus; nimbostratus

Warm Front Weather

1 2 3 4

1. Cold Front2. Warm Front

3. Stationary Front4. Occluded Front

Front Symbols

Triangles or hemispheres point in the direction its moving.

Figure from Project Datastreme

Weather in Pressure Systems

• High Pressure (Anticyclone)– Clear Sky; Light Wind– Clockwise circulation, – Sinking air

• Low Pressure (Cyclones) - STORMS– Overcast; Precipitation– Counterclockwise circulation – rising air