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Large bodies of air that have similar temperature and moisture properties
throughout are called what?
A. air currents
B. fronts
C. air masses
D. hurricanes
What are huge clumps of air that move around the Earth, bringing changes in
weather?
A. Air masses
B. Fronts
C. Storms
D. currents
Air masses are like the surface they form over. The air mass shown above formed
over land in northern Canada. Therefore the air mass will be
A. Warm and moist
B. Cold and moist
C. Cold and dry
D. Warm and dry
6. E.2B.2:
Develop and use models to
explain how relationships
between the movement and
interactions of air masses,
high and low pressure
systems, and frontal
boundaries result in weather
conditions and storms
(including thunderstorms,
hurricanes and tornadoes).
What’s at the boundary of any air mass?
•
•
Fronts!
•
A cold air mass may have
a cold front.
A warm air mass may have
a warm front.
A front is the boundary separating air masses
of different densities
 Fronts extend both vertically and
horizontally in the atmosphere
https://app.discoveryeducation.com/lear
n/videos/7053d665-da3f-444e-9a74fd3faff0035d?hasLocalHost=false
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Types of Fronts…
• Depending on the air masses
involved…four different types of front
may occur:
•
•
•
•
Warm Front
Cold Front
Stationary Front
Occluded Front
The Four Types
All of these fronts work using the law
of convection.
What is the Law of
Convection????
It states that energy can be
transferred from one
system to another, but it
cannot be destroyed
Stop and Think….
• What do you think would happen
when a warm air mass meets a cold
air mass?
• What do you think would happen
when a cold air mass meets a warm
air mass?
What’s Happening During A…?
Stationary
Cold
Warm
Warm Air
Faces Cold Air.
NO ONE
MOVES
Warm Air is pushed
up between two
cooler air masses
Occluded
Warm air
Rising Over
Cold Air
Cold Air is Rising
Over Warm Air
The Cold, Occluded, and Stationary Fronts Result
in PRECIPITATION!
http://www.phschool.com/atschool/phsciexp/active_art/weather_fronts/
Cold Front
•
Imagine this:
•
•
•
•
Warm air is hanging out
Cold air mass comes along and bumps warm it
What happens?
•
Cold air pushes warm air up (because warm air rises
and cold air sinks)
•
Cold front is formed
Weather
•
•
Cooler temperatures
Can cause thunderstorms and tornadoes
1. Cold Front: The zone where cold air is
replacing warmer air
• In U.S., cold fronts usually move from
northwest to southeast
• Air gets drier after a cold front moves
through
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Warm Front
• Imagine This..
•
•
Cold air is hanging out
Warm air mass comes along and bumps into it
• What happens?
•
•
Warm air moves over cold air
Warm front is formed
• Weather:
•
•
Long periods of precipitation
Warmer temperatures
2. Warm Front: The zone where warm air is
replacing colder air
• In U.S., warm fronts usually move from
southwest to northeast
• Air gets more humid after a warm front
moves through
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http://studyjams.scholastic.com/studyjams/jams/science/weath
er-and-climate/air-masses-and-fronts.htm
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Which is the correct definition of a weather front?
A.
B.
C.
D.
the boundary separating two air masses that have different conditions
the boundary of air that separates hurricanes from the ocean
the area between a storm cloud and the ground
the air mass that separates the atmosphere from the weather
This symbol is used on a weather map to represent a body of moving air that is
sometimes associated with fog. This symbol is used to represent a/an —

A.
B.
C.
D.
stationary front.
warm front.
cold front.
occluded front.
What does the curved line with triangles on the map represent?
A.
B.
C.
D.
a stationary front
a low pressure system
a warm front
a cold front
Stationary Front
• Imagine this
•
Warm air and cold air are moving toward each
other
•
•
They bump into each other
Neither moves!
• What happens?
•
Stationary front is formed
• Weather
•
Long periods of precipitation
3. Stationary Front: When either a cold or
warm front stops moving
• When the front starts moving again it
returns to either being a cold or warm
front
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• Imagine this
•
•
Occluded Fronts
Warm air is hanging out behind cool air
Cold air comes along and bumps into warm
air
• What happens?
•
•
Warm air moves over to cooler air masses
Occluded front is formed
• Weather
•
•
Long period of precipitation
Severe storms
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
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What weather feature forms at the boundaries between the air masses
as they move and collide?
A.
B.
C.
D.
storms
low pressure systems
systems
Fronts
A stationary front that produces long periods of precipitation occurs
when —
A.
B.
C.
D.
both a cold air mass and a warm air mass moves at a frontal boundary.
two cold air masses move at a frontal boundary.
neither a cold air mass nor a warm air mass moves at a frontal boundary.
two warm air masses move at a frontal boundary.
Which statement describes an occluded front?
A.
B.
C.
D.
warm air gets caught between two cold air masses
warm and cold air meet and neither air mass can move the other
cold air pushes up and under a moist, warm air mass
moist, warm air moves up and over a cold air mass
http://studyjams.scholastic.com/studyja
ms/jams/science/weather-andclimate/air-masses-and-fronts.htm
https://www.wunderground.com/maps/u
s/Fronts.html
Fronts Foldable
Draw an illustrations of the four different types of
fronts and explain what is taking place, include
definition and weather associated with each Front .
Resource Pass Book p 136 or Textbook p 280
ONCE YOU FINISH COMPLETE Lesson in PASS BOOK
p135-138
Which statement about weather fronts is correct?
A.
B.
C.
D.
A warm front generally moves from northeast to southwest.
A warm front is when a cold air mass rides over a warm air mass, resulting in rain.
A cold front is when a cold air mass pushes a warm air mass to the side.
A cold front is when a cold air mass slides under a warm air mass, resulting in
showers and thunderstorms.
This symbol is used on weather maps to represent a body of moving air
that is often associated with a low pressure area. This symbol
represents a/an —
A.
B.
C.
D.
warm front.
occluded front.
stationary front.
cold front.
A warm front usually moves more slowly than a cold front because —
A.
B.
C.
D.
cold air is denser and hard to move along Earth’s surface.
cold air is lighter and hard to move along Earth’s surface.
cold air is more moist and hard to move along Earth’s surface.
cold air is drier and hard to move along Earth’s surface.
6. E.2B.2:
Develop and use models to
explain how relationships
between the movement and
interactions of air masses,
high and low pressure
systems, and frontal
boundaries result in weather
conditions and storms
(including thunderstorms,
hurricanes and tornadoes).
https://www.brainpop.com/science/weather/
weather/
Warm air rising or cold air
sinking combined with the
spinning of the Earth causes the
air to spin forming high and low
pressure regions.
• High pressure
causes air to sink
• Usually results in
several days of clear
sunny skies
• Air rises in low
pressure areas
and forms water
droplets
• Can results in
rain and storms
http://studyjams.scholastic.com/studyjams/jams/science/weatherand-climate/air-pressure-and-wind.htm
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•High pressure systems usually signal more fair
weather with winds circulating around the system in a
clockwise direction.
•Low pressure systems with counterclockwise
circulating winds often result in rainy and/or stormy
weather conditions.
HEAVY
LIFT
Highs & Lows Video 1:33
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Using TEXTBOOK P 282 DRAW high
and low pressure with the arrows
Low Pressure and Fronts Cause Lift
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Weather Maps: Pressure &
Temperature
https://app.discoveryeducation.com/learn/videos/c6ad0e08
-0dd4-4d38-831a-64466940f84d?hasLocalHost=false
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Air Pressure
•Place the empty can a few
inches apart on a flat surface.
•Blow between the two cans from
directly above them
•Observe what happens
•Set the can up again, blow
horizontally between the cans
from direct level of the flat
surface they are on
•Observe what happens
•
•
What did you observe?
•
The cans rolled away from each
other, when blowing down
between the cans, you increased
the air pressure between them
•
The second time, when you blew
horizontally the can rolled
together, this time you lessened
the pressure between the cans.
This was to show what happens
when air pressure changes
•
As you blew horizontally, you
cleared out the air between the
can therefore creating an area
of low pressure.
•
The higher the pressure on the
outside of the can pushed the
cans together towards the area
of lower pressure.
•
As the speed of air increases,
the pressure id the air
decreases and the faster the air
moves the less pressure it has.
If someone ask you to
explain fronts and air
masses, what would
you say? Use details
and illustrations…
Storms
Storms
· Severe weather conditions
called storms occur when
pressure differences cause
rapid air movement.
· Conditions that bring one kind of storm can also
cause other kinds of storms in the same area.
•Types: Thunderstorm, Tornado, Hurricane
Severe Weather 15:09
Monsoons 11:21
Rain or Shine: Understanding the Weather Video 13:44
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Thunderstorm
•is a storm with thunder, lightning, heavy
rains and strong winds;
•Require 3 conditions to form:
• moisture, instability, source of lift
•form within large cumulonimbus clouds;
•usually form along a cold front but can form
within an air mass.
Thunderstorm Formation Animation
Weather Smart Video 14:59
Lightning Animation
Real Thunderstorm Animation
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•A tornado
• is a rapidly whirling, funnelshaped cloud that extends down
from a storm cloud
•the very low pressure and strong
winds can cause great damage to
people and property.
•Tornadoes are likely to form
within the frontal regions where
strong thunderstorms are also
present.
Tornado Wind Patterns Animation
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•A hurricane
• is a low pressure tropical
storm that forms over warm
ocean water;
•winds form a spinning
circular pattern around the
center, or eye, of the storm.
•The lower the air pressure at
the center, the faster the winds
blow toward the center of the
storm.
Science Daily- Hurricanes
•https://www.youtube.com/watch?v=c2XVZGpMwS4
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Remember!!
Weather is also cold
air, cloudy days,
sunny days, etc. Not
always storms!
https://www.youtube.com/watch?v=GGu
-Dcd-9-s
https://app.discoveryeducation.com/lear
n/videos/c6ad0e08-0dd4-4d38-831a64466940f84d?hasLocalHost=false
What things make hurricanes
lose strength?
Crumble a piece of paper,
flatten it and repeat
Spin the top on the flattened
piece
Count the seconds until it
stops spinning
Repeat but this time spin on a
smooth surface and count