Download Air Masses

Composition of the Atmosphere
Layers of the Atmosphere
• The Troposphere:
• The lowest layer
of the
atmosphere; next
to the Earth’s
surface.
• It’s where most
weather takes
place.
• The Stratosphere:
• Home of the Ozone
Layer
• The atmospheric
layer above the
troposphere.
• The Mesosphere:
• The Middle Layer
• It is also the coldest
layer.
• The Thermosphere:
• The uppermost edge of the
atmosphere
• Contains the Ionosphere:
• Home of the Auroras
• In the upper mesosphere
and the lower
thermosphere, nitrogen
and oxygen atoms absorb
harmful solar energy.
EXIT SLIP:
Create a T chart: on one side
labeled “What I know,” and the
other “What I have learned.”
Objectives
• I will know how air masses become fronts
• I will be able to explain the difference
between the four different types of fronts.
Weather Foldable
• Open the Large
pocket and
label Types of
Fronts on top
and Air Masses
on the bottom
panel.
Weather Foldable
• Close it up
and write 2
more
headings:
Layers of the
Atmosphere
and Highs and
Lows.
Label the Air Masses picture!
• **Put the next
notes under your
AIR MASSES
heading**
Air Masses
An air mass is a large body of air that has fairly uniform
physical properties, such as temperature and moisture
content.
Write these notes to the
left of the Air Masses
picture.
Air Masses cont’d
Air masses are classified according to whether
they form over water or land, and the latitude
where they form.
U
Paste FRONTS pictures
on left
Make a Chart with 2
headings: “How it
Forms” and
“Weather it Brings”
Fronts (Look and Listen!!)
Air masses move with the circulation of air
throughout the planet.
• When different air masses meet, they ordinarily
don’t mix. Instead, a boundary forms between them,
called a FRONT.
Fronts
A cold front forms when a cold air mass overtakes a
warm air mass.
Cold fronts often bring strong winds, severe thunderstorms, and
large amounts of precipitation.
Rising
warm
air
Direction
of front
Cold air mass
sinks under the
warm air mass.
Label the drawing provided in
your notes appropriately.
Precipitation
Fronts
A warm front occurs when a warm air mass
overtakes a cold air mass.
Occasionally heavy showers or thunderstorms occur.
Clouds form as
rising moist, warm
air condenses.
Rising
warm air
Direction
of front
Cold air mass
sinks under the
warm air mass.
Label the drawing
provided in your notes
appropriately.
Precipitation
Fronts
Stationary Fronts
• When two unlike air
masses have formed a
boundary but neither is
moving, the front is
called a stationary front.
• Stationary fronts often
result in clouds and
steady rain or snow for
several days.
Label the drawing provided in
your notes appropriately.
Fronts
Occluded Fronts
An occluded front forms when a warm air mass is
caught between two cooler air masses.
• Occluded fronts usually bring cloudy skies and
precipitation.
Label the drawing provided in
your notes appropriately.
Cold Front
Warm Front
Stationary Front
Occluded front
Objectives
• I will know how different storms form and
how they produce damage.
• I will be able to explain the difference
between a cyclone and anticyclone.
Low- and High-Pressure Systems
Air masses are part of larger weather systems.
Weather systems are organized around either a
center of high air pressure or a center of low air
pressure, and may include more than one type of
air mass.
•Low Pressure is generally bad weather
•High Pressure is generally good weather.
• First 10 minutes– label
the cutout of the layers
of the atmosphere and
glue it under your
heading, “Layers of the
Atmosphere.”
• Finish the “Fronts”
notes from yesterday.
Now, on the bottom of the Highs
and Lows flap…
Low- and High-Pressure Systems
Cyclones (Lows)A weather system with a
center of low air pressure is called a cyclone.
• Because air moves from high-to lowpressure areas, air spirals in toward the
center of a cyclone. Generally BAD
weather.
Anticyclones (Highs)A weather system
with a swirling center of high air pressure is
called an anticyclone
• Because the center of an anticyclone
has high pressure, air flows away from
that center. Generally GOOD weather.
Pressure Gradient Force
• Air flows from
high pressure
to low
pressure.
• This is why the
wind blows!
Storms and Precipitation
• You’ll make 2 Post-It Flip Books on the back of
your foldable; one labeled STORMS; the
other, PRECIPITATION.
Storms
Thunderstorms: Cold front lifts warm, moist air quickly,
forming a cumulonimbus cloud. The result is lightning,
thunder, and heavy rains. Heavy T-Storms, like
supercells, are dangerous because they tend to drop
tornadoes!
Storms
Tornadoes
•Intense windstorms that
take the form of a rotating
column of air that touches
the ground.
•Tornadoes most often
form at the leading edge
of an advancing cold front.
Storms
Tropical Storms and Hurricanes
Cyclones also develop in the tropics, where they can
develop into tropical storms or hurricanes.
A hurricane is a large tropical cyclone with winds of at
least 119 kilometers per hour (74 miles per hour). They
are fueled by moist, warm air. This is whey they die
when they make landfall.
Precipitation
• Snow: Ice crystals that vary due to the temp at which
they form.
Precipitation
• Rain: Collision and coalescence of water in the
atmosphere. All rain begins as ICE!
• Sleet: Falls through a cold layer of air, then a warm
layer, then another cold layer.
More winter Stuff…
• Freezing rain: Like sleet, but the cold layer at the
surface is much thinner, so it doesn’t solidify before
hitting the ground. It solidifies after.
More winter Stuff…
• …Other weird stuff:
• Virga: Precipitation that doesn’t reach the ground.
More winter Stuff…
• Graupel: Pellet-like snowy stuff that forms when lots
of supercooled water and ice accrete before falling.
Usually happens on mountains.
Awwww HAIL no….
• Hail: Happens when a T-Storms updraft is so strong
that ice crystals just bounce and grow until they
become heavy and fall.
Wow That’s Fantastic
• Frogs: Not kidding. A small water-tornado called a
waterspout can carry small organisms (tadpoles,
frogs) into the air and dump them on land when it
dissipates.