Download October 28th presentation

October 28th, 2014
You have until 10:05 to
complete the warm up
Today’s Objectives:!
Describe qualities of air masses and air fronts
Warm Up
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Under what air pressure condition do clouds form?
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Low pressure!
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What temperatures are associated with low pressure?
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Warm Temperatures!
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As water molecules condense what happens to their
density.
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The density increases
Rain Analysis
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1. What three steps of the water cycle did you observe.!
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We observed Evaporation, Condensation, and Precipitation!
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1.When water evaporates it becomes “clean”, leaving any toxins behind. Why do
you think this is important to the health of the Planet?!
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Evaporation is important to clean water because it provides a source of clean
water for the rest of the cycle and helps prevent the movement of pollution.!
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3. Describe how the model works using the following terms; evaporation,
condensation, precipitation, gas, liquid, dense, less dense, gravity. !
As the water heats up it becomes less dense and evaporates. Evaporation is
when water turns from liquid to a gas. As the water vapor rises it condenses on
the small pot of ice and begins to cool. As it cools the water vapor becomes
dense and turns back into a liquid. When the water becomes dense enough
gravity makes the water fall in the form of precipitation.
Cloud Analysis
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1.Why did we add smoke to the bottle?
We added smoke to help the clouds become more visible in Nature clouds form using dust
and water vapor.
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2.What happened to the pressure of the air when you squeezed the bottle and why?
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The air pressure increased because there was less space for the air molecules to move around.
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3.Use your own words to describe how air pressure and cloud formation are related.
Clouds form under low air pressure because air is flowing into the clouds instead of
outwards like it would in high pressure.
Why is there weather?
There are 2 reasons:
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1. The movement of air masses;
2. The movement of fronts.
Air Masses
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A large dome of air which has
similar horizontal temperature
and moisture characteristics
throughout.
Where would you expect to find cold air
masses? Warm Air Masses?
Where would you expect
to find cold air? warm air?
How do Air Masses move?
•
http://www.classzone.com/books/ earth_science/terc/conten
visualizations/es2001/ es2001page01.cfm?
chapter_no=visualization
!
• All around the earth, large masses of air move around and
constantly change the weather.
How do We identify Air
Masses
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We ask two questions
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Where did it form? Over Land (Continental) or over
water (Maritime)
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Where is the mass coming from? From the Poles
(Polar) or from the Equator (Tropical)
Continental Polar
!
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• Cold, dry, and stable
• Originates in Canada and influences Northern U.S.
• Responsible for clear, pleasant weather during the
summer
• Responsible for lake effects snow around the Great
Lakes in winter
Maritime Polar
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• Cool, unstable, and moist
• Originates over icy waters of the northern Atlantic and Pacifi
Oceans and mainly influences Pacific Northwest and
Northeast
Continental Tropical
!
• Warm, stable, and dry
• Originates over Mexico and affects the Midwest
• Responsible for hot dry summers and warm dry winters
Maritime Tropical
!
• Warm, unstable, and moist
• Originates over southern Atlantic and Pacific Oceans and
mainly influences Pacific Southwest, Midwest, Northeast, and
Southeast
What type of weather would the
following air masses bring?
Wednesday, January 22, 14
Lab: Diagram and label each
air mass affecting the U.S.
Color code your diagram.
Fronts
• The Earth has 4 major air masses, two
warm ones and two cold ones. When
those air masses run into each other,
the place where they meet is called a
front.
• Fronts are responsible for all kinds of
weather like snow and storms.
Study Jams air masses and fronts
Wednesday, January 22, 14
Fronts
• A boundary created when two air
masses meet.
• Fronts are named for the air mass that
is moving.
Wednesday, January 22, 14
Fill in the “Weather Fronts” chart
as you follow along the next few
Wednesday, January 22, 14
Cold Front
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Cold dense air moves in and pushes
warm air out of the way
Cold fronts move very quickly and
bring short periods of rain/
thunderstorms
Lower temperatures are behind the
front
SYMBOL – the direction of the
Wednesday, January 22, 14
Warm Front
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•
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Warm air moves up the cold front as
it slowly displaces and overtakes the
cold air
Warm fronts move slowly, and bring
many days of steady precipitation
Higher temperatures are behind the
front
SYMBOL – direction of “half-moons” is
Wednesday, January 22, 14
Stationary front
• Created when cold and warm masses
meet but neither one has enough force
to move the other out of the way.
• The water vapor in the warm air
condenses into rain, fog, snow, clouds.
• Can bring many days of precipitation
Wednesday, January 22, 14
Wednesday, January 22, 14
Occluded front
• Is created when a warm air mass is
caught between two cooler air masses.
• The two denser cooler air masses cut
off the warm air mass from the ground.
• As the warm air mass cools, it may
turn cloudy, rainy or snowy.
Do a weather report
Wednesday, January 22, 14
Homework
Summarize
• Why does the Earth experience
weather?
Write an introductory paragraph, a
paragraph explaining air masses and
how they affect Earth’s weather, a
paragraph explaining fronts and how
they affect Earth’s weather, and a
closing paragraph.