warm and occluded fronts. today cold fronts warm fronts occluded fronts
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Warm and occluded fronts
Today
• Cold fronts
• Warm fronts
• Occluded fronts
Idealized Cold Front
Isotherms
0C 5 10 15 20 25 30C
100 km
Frontal Zone
44 75
COLDFRONT
Idealized Cold Front
Cross-sectional Characteristics
Cold Air
Warm Air
Strong Lifting near thefrontal boundary can produce convective clouds.
Idealized Cold Front
Cold Air Warm Air
Idealized Cold Front
• Precipitation:
– Located on either side of the front.
– Convective, showery in nature
– If warm air is stable
• Nimbostratus, Altostratus
– If warm air is unstable
• Cumulus, Cumulonimbus, Thunderstorms
Idealized Cold Front
© 1999 Prentice-Hall, Inc. -- From: Aguado and Burt, Understanding Weather and Climate
Cold Air Warm Air
Surface Front
Idealized Warm Front
Isotherms
30C 25 20 15
100 km
Frontal Zone
83
WARMFRONT
66
Idealized Warm Front
• Warm Front
– A boundary that moves in such a way that the colder (more dense) air retreats and is replaced by the warmer (less dense) air.
– The warm fronts tend to have weaker temperature gradients.
Idealized Warm Front
Cross-sectional Characteristics
Warm Air
Cold Air
Weaker lifting near thefrontal boundary oftenproduces stratiformclouds.
NsAs
Cs Ci
Idealized Warm Front
• Precipitation:
– Located on the cold side of the front.
– Stratiform, more persistent in nature
– In winter, precipitation may fall as sleet or freezing rain.
Idealized Warm Front
© 1999 Prentice-Hall, Inc. -- From: Aguado and Burt, Understanding Weather and Climate
Stationary Front
• Frontal boundary that either does not move or moves very slowly.
• Stationary fronts can “wash out” as the air masses on both sides of the front become the same.
Occluded Fronts
• Cold fronts typically move faster than warm fronts.
• Cold fronts can catch up and “overtake” a warm front.
• Depending on the different air masses, there are two types of occlusions:
– Cold type occlusion
– Warm type occlusion
Cold-Type Occlusion
Cold Air
Cool Air
Warm Air
Warm-Type Occlusion
Cold AirCool Air
Warm Air
Summary
• 4 types of front
• Weather comes with fronts