Air Masses and Fronts
Air Mass
• Large body of air with uniform temperature
and humidity
• Air masses take on the characteristics of the
region from where they originate
• Continental (dry)
• Maritime (moist)
• Polar (cold)
• Tropical (warm)
Fronts
A front is the boundary separating air masses of different
densities
 Fronts extend both vertically and horizontally in
the atmosphere
Classified by what type of air mass is replacing
another
Where most weather takes place
NSF North Mississippi GK-8
Types of Fronts
•
•
•
•
•
Cold front
Warm front
Stationary front
Occluded front
Dry Line front
• Each represented by these symbols on a
weather map
Fronts: Five Types of Fronts
1. Cold Front: The zone where cold air is replacing
warmer air
• In U.S., cold fronts usually move from northwest to southeast
• Slope of front is steep so warm air forced up abruptly
• Creates rain and thunderstorms along front
• Air gets drier after a cold front moves through
NSF North Mississippi GK-8
Fronts: Five Types of Fronts
2. Warm Front: The zone where warm air is replacing
colder air
• In U.S., warm fronts usually move from southwest to
northeast
•Slope of front is gentle so creates a line of stratus clouds and
precipitation
• Air gets more humid after a warm front moves through
NSF North Mississippi GK-8
Fronts: Five Types of Fronts
3. Stationary Front: When either a cold or warm front
stops moving ( they are in a standoff)
•Bring several days of cloudy, wet weather that
can last a week or more.
• When the front starts moving again it returns to
either being a cold or warm front
NSF North Mississippi GK-8
Fronts: Five Types of Fronts
4. Occluded Front: Formed when a cold front
overtakes a warm front
• This occurrence usually results in storms over an
area
• In U.S., the colder air usually lies to the west
NSF North Mississippi GK-8
Fronts: Five Types of Fronts
5. Dry Line (Dew Point Front): Boundary separating a
dry air mass from a moist air mass
 This occurrence can result in tornadoes being
formed
 Usually found in western part of U.S.
NSF North Mississippi GK-8
• New Area of Focus: Fronts
• Warm Fronts and Cold Fronts are caused by
air pressure.
Copyright © 2010 Ryan P. Murphy
• Remember: Cold sinks, warm rises
• Cold Front: Form where cold air moves
towards warm air.
– Creates rain storms.
Copyright © 2010 Ryan P. Murphy
• Cold Front: Form where cold air moves
towards warm air.
– Creates rain storms.
Copyright © 2010 Ryan P. Murphy
• Cold Front: Form where cold air moves
towards warm air.
– Creates rain storms.
Copyright © 2010 Ryan P. Murphy
Direction of
travel
Direction of
travel
Cold
Cold
Warm
Cold
Warm
m
Cold
Cold
Cold
Cold
Cold
Warm
Cold
Warm
Cold
Wa
Cold
“Honey, I think
it’s time to get
our stuff
together.”
Cold Air
Warm Air
Cold Air
Warm Air
Cold Air
Rain
• Video (Optional) Cold Front Time Lapse.
– http://www.youtube.com/watch?v=i8zq0UXPLX0
• Warm Front: Form where warm air moves
towards cold air.
Copyright © 2010 Ryan P. Murphy
Warm
Warm
Cold
old
Warm
Warm
Warm
• Occluded front: When a cold front overtakes
a warm front and forces it up (Mix)
Copyright © 2010 Ryan P. Murphy
• Occluded front: When a cold front overtakes a
warm front and forces it up (Mix)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and
warm front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Stationary Front: When a cold front and warm
front cannot overtake each other (tie)
Copyright © 2010 Ryan P. Murphy
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Please match the name of the front to the
picture.
– Warm Front, Cold Front, Occluded Front,
Stationary Front
A
B
C
D
• Challenge Activity! Which letter best
represents a warm front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a warm front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a cold front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a cold front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents an occluded front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents an occluded front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents an occluded front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a stationary front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a stationary front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a stationary front?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents high pressure?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents high pressure?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents low pressure?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents low pressure?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a cyclone?
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a cyclone? Answer: A
F
A
E
B
C
D
• Challenge Activity! Which letter best
represents a cyclone? Answer: A
F
A
E
B
C
Weather fronts. Learn more at…
http://www.windows2universe.org/earth/At
mosphere/front.html
Weather map fronts. See more at…
http://www.nws.noaa.gov/outlook_tab.php
D
• Video Link Before Quiz
– Weather forecasting, fronts, Isobars and more.
– http://www.youtube.com/watch?v=lITCF3UPVu4
• Quiz 1-10 Name the Front. Warm, Cold,
Occluded, Stationary, Other.
Copyright © 2010 Ryan P. Murphy
6
• Bonus -1 pt for each character (1 minute)
Copyright © 2010 Ryan P. Murphy
• Answers: Name the Front. Warm, Cold,
Occluded, Stationary, Other.
Copyright © 2010 Ryan P. Murphy
6
6
Weather Maps
How to read Weather Maps
• There are weather stations all over the world
• These stations report on their current weather
using symbols
• This data is plotted and a view of conditions
are seen
Station Model
How to read
•
•
•
•
Temperature
Weather conditions
Dew point
Atmospheric
pressure
• Wind direction and
speed
Wind Barbs
• Wind Direction is
stated where it is
blowing FROM
• This is blowing from
southeast
• Feathers show how
fast blowing
– Full feather = 10 knots
– Half feather = 5 knots
– Little feather = 1 knot
Isobars
Temperature Maps
Isobars
• ‘iso’ = equal
• “bars” = barometeric pessure
•
•
•
•
Shows line of equal atmospheric pressure
Lines close together = strong winds
Lines further apart = gentler winds
Generally measured in 4 millibar increments
• Can also have isotherms on weather maps (measured
in 10 degree increments)
Wind Directions
• Low pressure system aka “cyclone”
– Winds blow in a counterclockwise direction
• High pressure system aka “anticyclone”
– Winds blow in a clockwise direction