Weather Air Masses and Fronts
Dec 22, 2015
Weather
Air Masses and Fronts
Air Masses• Function of location (arctic – A, polar – P, tropical – T) and
surface type (continental – c and maritime – m)
Fig. 15.5
What do you notice about the pressure at the north pole?
What about at ~ 30oN and 60oN?
Why does this pattern occur, and what is happening?
Air mass movement
and consequences
Fig. 15.6
Daily QuestionUse a Venn diagram to compare and contrast the characteristics of warm fronts and cold fronts. Identify at least 7 features
1615
2 5 8 1012 14
3 4 7 911 13
• Cold Front• Air mass is cold
behind the front.• Advancement forces
the warm air up (rapidly)– clouds form
• Warm Front – • Air mass is warm behind the front• Warm is relatively stable – moves slower than cold
front• Slowly over take cold air (slight precipitation as front
passes)• Clear and sunny behind front prior to cold front• Stationary Front – front is moving very slowly• Occluded front – cold front has caught the warm front
Frontal Systems
Fig. 15.10
Fig. 15.12
Midlatitude Cyclones
• Regional Scale low pressure system
• A result of a collision of polar and tropical air masses
Fig. 15.13
• Generally start as a stationary front where cP air and mT air collide
Shearing causes
the northward
movement of
the tropical air and
the southward
movement of
the polar air to create a
counterclockwise rotation of the air masses.Fig. 15.14.a
• Warm air continues to migrate north and to the east
• Cold air continues to migrate south and to the east.
Cold air moves
about 2x faster
than warm air.
Thus, the cold
air will overtake
the warm air and
create a an
Occluded front.
Fig. 15.14.b
Fig. 15.14.c
Wave-cyclones & Mid-Latitude Storms
Deciphering a weather map
Tomorrow’s Weather
Wednesday’s Weather