1. Warm and occluded fronts

2. Today
Cold fronts
Warm fronts
Occluded fronts

3. Idealized Cold Front Isotherms COLD FRONT 75 44 0C 5 10 15 20 25
100 km
COLD
FRONT 75 44
0C 5
10
15
20
25
30C
Frontal Zone

4. Idealized Cold Front Cross-sectional Characteristics Warm Air Cold Air
Strong Lifting near the
frontal boundary can
produce convective
clouds.

5. Idealized Cold Front
Cold Air
Warm Air

6. 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

7. Idealized Cold Front Warm Air Cold Air Surface Front
© 1999 Prentice-Hall, Inc. -- From: Aguado and Burt, Understanding Weather and Climate

8. Idealized Warm Front Isotherms WARM FRONT 83 66 30C 25 20 15
100 km
WARM
FRONT 83 66
30C
25
20
15
Frontal Zone

9. 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.

10. Idealized Warm Front Cross-sectional Characteristics Ci Cs Warm Air AsNs
Cold Air
Weaker lifting near the
frontal boundary often
produces stratiform
clouds.

11. 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.

12. Idealized Warm Front
© 1999 Prentice-Hall, Inc. -- From: Aguado and Burt, Understanding Weather and Climate

13. 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.

14. 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

15. Cold-Type Occlusion
Warm Air
Cold Air
Cool Air

16. Warm-Type Occlusion
Warm Air
Cold Air
Cool Air

17. Summary
4 types of front
Weather comes with fronts