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4/25/2015
1
Mixture of Gases in Air
All Other Gases
Argon = 0.93%
Carbon Dioxide = 0.04%
Largest Jar = ____ sec Medium Jar = ____ sec Small Jar = ____ sec
21% Oxygen in all Jars – but that equals a
smaller amount of oxygen in a small jar
How long will the candle burn?
Largest Jar = ____ sec Medium Jar = ____ sec Small Jar = ____ sec
1)
2)
Mixture of Gases in Air
All Other Gases
Argon = 0.93%
Carbon Dioxide = 0.04%
NITROGEN
• A major part of proteins, including
DNA
• Dilutes (thins out) the oxygen – too
much or too little oxygen and we
would die!
• Turned into useful form
by nitrogen-fixing bacteria
OXYGEN• Necessary to survive!
• Our cells use oxygen to
create energy
• All of the oxygen in our
atmosphere has been
created by plants –
photosynthesis!
• Burning requires oxygen
CARBON DIOXIDE
• Used by plants for photosynthesis
• A greenhouse gas – carbon dioxide
helps keep our planet warm
• Increases in CO2 have been making
the planet warmer: global warming!
TRACE GASES
• OZONE helps filter out the
sun’s harmful rays
• ARGON is used in light bulbs
because it will not catch fire
even in extreme heat
• WATER VAPOR can condense
to form clouds
• HELIUM inflates balloons and
blimps
WRITING IN SCIENCE
• Write a paragraph that
summarizes in your own
words how oxygen from the
atmosphere is important.
Include its importance to
living things and in other
processes.
Why is the atmosphere important?
• Has oxygen that living things
need to survive.
• Traps energy from the sun
keeping earth warm
• Protects living things from
dangerous radiation from the
sun.
4/25/2015
2
Exploring Air with SyringesToday, you will investigate air with syringes and
tubing – work on your own or with your group.
In your science notebook, copy and
answer the following questions:
1) What happens to the air in the syringe
when you push/pull on the plunger?
2) What can air do?
3) Record 3 observations & 1 question.
*SAFETY – Be careful with the materials! Do not
point either end of the syringe at another student.
Exploring Air with SyringesBased on the investigation:
What can air do?
A few words you need to know…
Compress – means to squeeze into a smaller
space
Density – the amount of mass (stuff) in a
certain amount of space (volume)
Air Pressure – the force of air pushing on stuff
Barometer – a tool that measures air pressure
Air Pressure in a SyringeWhich syringe has the air under greater pressure?
High
Pressure
Low
Pressure
Air Pressure in a BalloonIs the density of air molecules in a balloon
greater than or less than the surrounding air?
Higher
Pressure
& Density
Lower
Pressure
& Density
Air Pressure at Different AltitudesIs air pressure greater at sea level or on top
of a mountain?
More
Pressure
& Density
Less
Pressure
& Density
Sea Level (Low altitude)
Mountains
(High altitude)
TROPOSPHERE• Thinnest Layer (0-12 km)
• Average Temperature of 25°C
(Temperature drops as you go higher)
• All of Earth’s weather happens here.
• Air here contains water & dust.
• Most of the atmosphere’s air is here (this
layer is very dense).
STRATOSPHERE• 10-50 km above earth’s surface
• There is almost no water or dust in this
layer.
• Contains the OZONE LAYER (which
absorbs UV radiation from the sun)
• Very cold, until the top of the layer,
where it warms to 0°C.
MESOSPHERE• 50-80 km above Earth’s surface.
• Temperature plunges to -90°C (the
coldest in the atmosphere)
• Meteors burn up here while entering the
atmosphere.
THERMOSPHERE• Thickest layer (80-400 km above Earth’s
surface).
• Air is extremely thin. Atmospheric gases
fade into outer space.
• Temperature can spike to 1,800°C.
4/25/2015
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What is
HEAT?What is “temperature?”
Where does our heat energy
come from?
Why do some things heat up
more than others on a hot day?
What do
“hot” and
“cold” really
mean?
What is heat, anyway?
• Temperature is a measure of the
average amount of energy of motion
for each particle of a substance
Cold
Water
Slow-
Moving
Molecules
What is heat, anyway?
• Temperature is a measure of the
average amount of energy of motion
for each particle of a substance
• Let’s act it out!
Hot
Water
Fast-
Moving
Molecules
Where does the energy come
from?
• Nearly all the energy that heats our
atmosphere comes from the sun.
• Not all sunlight reaches the ground.
Some sunlight is absorbed or
reflected before it reaches the
surface.
Where does the energy go? Where does the energy go?
Where does the energy go?
• Not all surfaces absorb the sun’s
energy equally.
• The color and material of the surface
will determine how much of the
energy is absorbed and how much is
reflected.
Water
Rocks
Grass
Sand
How does heat move?
• HEAT is the transfer of thermal
energy from a hotter object to a
cooler one.
• Thermal
energy is moving
from the air,
which is
warmer, to the
snowman, which
is cooler.
How does heat move?
• Heat can be transferred in three
ways: radiation, conduction, and
convection.
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RADIATION
• Radiation is the direct transfer of
energy by electromagnetic waves.
• Radiation does not need any material
to travel through!
• Energy from the sun gets to us
through radiation.
CONDUCTION• Conduction is the direct transfer of heat
from one material to another that is
touching it.
• When a faster-moving molecule bumps into
a slower-moving molecule, the slower one
speeds up.
• Conduction works best in solids.
Metal is a
good
conductor –
the heat
moves to the
girl’s hand.
Wood is
not a good
conductor.
CONVECTION
• Convection is the transfer of heat by the
movement of particles in a fluid (liquid or
gas).
• As fluids heat up or cool down, their
density changes. Lower-density materials
will rise above higher-density materials.
HEAT TRANSFERRadiation, Conduction, or
Convection?
• You feel the warmth of the
sun’s rays on your face
outside.
• You notice your macaroni
moving up and down in the
boiling water.
• At the beach, you step on the
hot sand and it burns your
feet.
RADIATION
CONVECTION
CONDUCTION
Water in the Atmosphere
Earth is called the “Water Planet”
• 71% of the earth’s surface is covered
by water.
• Water is essential for LIFE on earth.
Water on earth’s surface is easy to see…
• Oceans
• Lakes
• Rivers
• Glaciers
But what about water in earth’s atmosphere???
Water in the atmosphereIt’s less obvious than surface water, but there are many signs of water in the atmosphere:
•Rain, Snow, Drizzle
•Clouds & Fog
•Hot days that feel “muggy” or “humid”
•Dew on the grassin the morning
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Water Cycle
• The movement of water between the atmosphere
and earth’s surface is the water cycle.
How does water get into the air?
• EVAPORATION – is the process where liquid water molecules escape into the airas water vapor.
• 3 things affect how quickly water evaporates:
1) Temperature
2) Wind
3) Humidity of the air
How much water can air hold?
• HUMIDITY is the measure of how much
water vapor is in the air.
• TEMPERATURE affects how much
water vapor the air can hold…
holds MORE water vapor. holds LESS water vapor.
That’s why air feels more “HUMID” on hot days!
What is the “Dew Point”?
• As air cools, the amount of water vapor it can hold decreases.
• At a certain temperature, the water vapor in the air will CONDENSE back into water droplets or ice.
• This temperature is the “DEW POINT”.
What is the “Dew Point”?
• So, when the air temperature equals the “Dew Point” temperature, the air cannot hold any more water.
That means relative humidity is 100%!
Ever wondered about why the grass (or a car windshield) is wet in the morning?
Overnight, the temperature droppedbelow the “dew point” temperature, and the water in the air condensed into water droplets on the grass.
CLOUDS
What are CLOUDS?• They are made of tiny water droplets or
ice crystals.
• They form when water condenses onto small particles in the air (like dust).
How TINY are the water droplets?
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How do clouds form?2) Air cools to dew point causing condensation.3) Water vapor condenses forming a cloud.1) Warm, moist air rises and cools. Clouds are NOT all the same…Flat clouds =
“Stratus”
Fluffy clouds =“Cumulus”
Wispy clouds =“Cirrus”
Clouds are classified according to SHAPE
Clouds are also classified by ALTITUDE
HIGH LEVEL (cirro-)
MID LEVEL (alto-)
LOW LEVEL (stratus)
On your blue paper, draw the different types of clouds (using chalk and charcoal).
*Use your textbook (pg. 111) and the cloud charts.*
Label each type of cloud.
Paste the paper into your science notebook.
Spot the cloud!
Low and flat …..
STRATUS
Middle level,
fluffy …..
Alto-Cumulus
Spot the cloud!
Spot the cloud!
High level, wispy …..
Cirrus
Spot the cloud!
Rain bearing, storm clouds …..
Cumulo-Nimbus
If you’re wearing a
black shirt on a
sunny day, you will
feel REALLY warm.
But if you’re wearing
white, you will stay
cooler.
4/25/2015
7
This is because dark
colors ABSORB
more sunlight than
lighter colors.
The air over
this part of
South
America
might be
cool…
While the air
over this part
is warmer.
This is called
UNEVEN
HEATING.
Cold air moves pretty slowly, and stays
pretty tightly packed together:
Hot air, on the other hand, goes really
fast and expands to fill more space.
So, hot air is LESS DENSE than cold
air.
• You should remember from our density column that less dense materials float
on more dense materials.
Closely packed for high density
Spread out for
low density
So, since hot air is less dense than the
surrounding air, it rises, leaving a low-
density, low-pressure area behind.
Low pressure
Nearby cold air can then rush in to fill low-
pressure area left by the rising hot air.
This rushing in of cold
air is what we call…
WIND!!
UNEVEN HEATING
The uneven heating of the air that causes
wind is created not only by different
colors on Earth’s surface, but also by:
• Different surfaces (grass vs. snow vs.
water, etc.)
• Pollution in some areas
• Different amounts of sunlight due to
seasons, clouds, etc.
4/25/2015
8
During the day, the air
over the sand is hotter
than the air over the
water because the
water takes longer to
heat up in the Sun.
So the wind in the
daytime blows
TOWARD the beach.
WARMER COOLER
But at night, the air over the
water is warmer than the air
over the sand, because
water HOLDS heat longer
than the ground.
So the wind blows toward
the ocean at night.
WARMERCOOLER
Sea Breeze
Land BreezeAir Masses
& Fronts
What is an AIR MASS?
• An air mass is a huge body of air that
influences weather.
• Scientists classify air masses based on:
TEMPERATURE and HUMIDITY
Air Masses are named based on where
they FORMED…
= TROPICAL
= POLAR
= MARITIME
(means sea… wet)
= CONTINENTAL
(means land… dry)
How are Air Masses named?
MARITIME
TROPICAL
MARITIME
POLAR
CONTINENTAL
TROPICAL
CONTINENTAL
POLAR
North American Air Masses
MARITIME
POLAR
CONTINENTAL
POLAR
MARITIME
POLAR
MARITIME
TROPICAL
MARITIME
TROPICAL
CONTINENTAL
TROPICAL
4/25/2015
9
How do these air masses move?
MARITIME
POLAR
CONTINENTAL
POLAR
MARITIME
POLAR
MARITIME
TROPICAL
MARITIME
TROPICAL
CONTINENTAL
TROPICAL
Jet Stream Jet Stream
Prevailing Westerlies
That’s why weather
generally moves
WEST to EAST
in the U.S.
What happens when air masses
meet?
• Air masses don’t mix easily.
• The line between air masses is called a
front.
COLD FRONTS
WARM FRONTSCompare/Contrast Chart - Types of Fronts
Front How it Forms Type of Weather
Cold
Front
A fast-moving cold air mass
overtakes a warm air mass.
Clouds form.
If warm air is humid,
rain/snow may fall.
Possible thunderstorms.
Warm Front A warm air mass overtakes
a slow-moving cold air
mass.
Scattered clouds.
Light rain or snow.
May last several days.
Stationary Front Cold and warm air meet,
but neither can move the
other. Creates “standoff”
Rain, snow, clouds, or fog
that may last for days.
Occluded Front A warm air mass is
caught between 2 cooler
air masses. Warm air
mass is pushed up.
Temperature gets
cooler.
Clouds and rain may
form.
Surface Map (Fronts & Precipitation)
Stationary Front
Occluded FrontWarm
Front
Cold Front
HHigh Pressure
LLow Pressure
Precipitation
Temperature Map
Stationary Front
Occluded FrontWarm
Front
Cold Front
HHigh Pressure
LLow Pressure
30°C
14°C
15°C
12°C
28°C 21°C
20°C
26°C
25°C
19°C
Monday Weather
Little Rock, AR
Sun & clear skies
Cool = 15°C
Tuesday Weather
Little Rock, AR
Clouds & Rain
Warmer = 21°C
Wednesday Weather
Little Rock, AR
Partly Sunny
Warmer = 26°C
Which direction is the warm
front moving?
What will happen to the
weather in Little Rock?
Stationary Front
Occluded FrontWarm
Front
Cold Front
HHigh Pressure
LLow Pressure
18°C
10°C
8°C
20°C
Thursday Weather
Nashville, TN
Partly Sunny
Warm = 20°C
15°C
11°C
10°C
10°C
Which direction is the
cold front moving?
What will happen to the
weather in Nashville?
Friday Weather
Nashville, TN
Thunderstorms
Cooler = 15°C
Saturday Weather
Nashville, TN
Sunny
Cool = 10°C
4/25/2015
10
Weather Tools
Thermometer
A thermometer uses an expanding liquid to
measure temperature.
Thermometer
► We will measure temperature using the Celcius scale.
Anemometer
► An anemometer measures wind speed.
Anemometer
► The unit we will use for wind speed is miles per hour (mph).
Hygrometer
► A hygrometer is used to measure humidity.
Hygrometer
►Humidity is measured in percents, where 100% would be the maximum amount of water the air can hold.
Barometer
► A barometer is used to measure air pressure.
Barometer
► The unit used for air pressure is the hectopascal (hPa). Normal atmospheric pressure is 1013.25 hPa.
4/25/2015
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Severe WeatherThunderstorms, Tornadoes,
Hurricanes, etc…
What is Thunderstorm?
•A thunderstorm is a small storm often accompanied by heavy precipitation and frequent thunder and lightning.
•Many thunderstorms form in the spring and summer in southern states or on the Western Plains.
How does thunderstorms form?
Thunderstorms form in large cumulonimbus clouds also known as thunderheads on hot, humid afternoons or when warm air is forced upward along a cold front.
What is Lightning?
• Lightning is created by friction between the rising updraft and the falling downdraft in a cumulonimbus cloud
• This friction creates a separation of charges (kindalike rubbing your feet across the carpet in your socks)
• Eventually there is a discharge between positive and negative charges, creating a “spark” (kinda like touching that doorknob and getting a shock)
• On a larger scale, that “spark” is a bolt of lightning
What is Thunder?
• When lightning strikes, the “bolt” can be as hot as 30,000 degrees
• The air surrounding that bolt of electricity expands rapidly (remember… warm air expands), and then contract quickly as it cools.
• Because of the extremely high temperatures, the air expands and contracts rapidly and breaks the sound barrier (767 mph)
• The thunder is this “sonic boom.”
Thunderstorm Damage
• The heavy rains during thunderstorms can flood low-
lying areas. Floods can occur when
– the ground is already saturated by heavy rains.
– The water can’t soak into the areas covered with buildings, roads, and parking lots.
– A flash flood is a sudden, violent flood that occurs
shortly after a storm.
• When lightning strikes the ground, the hot,
expanding air can shatter tree trunks or start forest fires.
• Stay out of water because it’s a great conductor of electricity.
Can you tell how far away a storm is?
• Yes, you can use thunder to tell how far away a storm is. Next time you see a storm, count the number of seconds between when you see the lightning and hear the thunder. Take the number of seconds and divide by 5 and that will tell you how far away the storm is in miles. For example: If you counted 10 seconds between the lightning and the thunder, the lightning is 2 miles away!
HailHail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher and higher into the sky until they freeze into ice. Once they become heavy, they will start to fall.
4/25/2015
12
SEVERE THUNDERSTORM WATCH - A severe
thunderstorm (damaging winds of 58 miles per hour or more, or 1" hail in diameter or greater) is
likely to develop
SEVERE THUNDERSTORM WARNING - A severe
thunderstorm (damaging winds of 58 miles per hour or more, or hail three-fourths of an inch in
diameter or greater) is taking place in your area.
DOWNDRAFT - A sudden descent of cool or cold air to
the ground, usually with precipitation, and associated with a thunderstorm or shower.
UPDRAFT - A warm column of air that rises within a
cloud. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud.
Tornadoes
Thought to be the 1st photograph of a tornado (1884)
What are Tornadoes?
• Violent windstorms that take the form of a rotating column of air, or vortex, that extends downward from a cumulonimbus cloud.
• Because of the lower pressure in the center vortex, air near the ground rushes into the tornado from all directions.
• Air streams inward, it is spiraled upward around the core until it eventually merges with the airflow or the parent thunderstorm deep in a cumulonimbus tower.
How does Tornado
Form?
When warm, moist air mass
from the Gulf of Mexico meets cool, dry air mass from
Canada, they create instability in
the atmosphere. A change in wind
direction and an increase in wind
speed with increasing height creates
an invisible, and horizontal spinning effect in the lower
atmosphere. Rising air within the
updraft tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation
Tornado Alley
• Tornadoes occur more often in the United States than in any other country.
• About 800 tornadoes occur in the United States every year.
• Weather patterns on the Great Plains result in a “tornado alley.”
• Tornado Alley states: Arkansas, Iowa, Kansas, Louisiana, Missouri, Nebraska, New Mexico, Oklahoma, South Dakota, Texas
Watches & Warnings
• Tornado Watch
–Conditions are ideal for a tornado to be created.
• Tornado Warning
–An actual tornado has been sighted in the area or is indicated by weather radar.
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13
Tornado Safety Tips• BEFORE A TORNADO:
– Have a disaster plan. Prepare a kit with
emergency food for your home.
– Have enough food and water for at least 3
days.
• DURING A TORNADO:
– Go to a basement, bathroom, closet, or under
a table
– Leave mobile homes and go to a shelter
– Leave automobiles and do not try to outrun a
tornado.
– If outside, go to a ditch or low lying area and lie flat
– Stay away from fallen power lines and any damaged areas.
4/25/2015
14
Tornado Safety Tips• AT SCHOOL DURING A TORNADO:
– All schools have a disaster plan, and
frequent drills.
– Go to school’s basement or rooms
and hallways away from windows
– Crouch down on your knees and protect your head with your arms.
• AFTER A TORNADO:
– Stay indoors until it is safe to come out.
– Check for injured or trapped people, without putting yourself in danger
– Watch for downed power lines
– Use a flashlight to inspect your home.
“What’s in our Air?”
We breathe constantly… without thinking about it.
But not everything in our air is healthful… there can be
harmful substances in our air called POLLUTANTS.
Air Pollution is a problem!Where does Air Pollution come from?
Some sources of air pollution are natural, but most air pollution is the result of human activities.
Natural Sources = ►Forest Fires
►Volcanoes
►Sand Storms
Which human activities release air pollution?
Burning Fossil Fuels
(such as coal, oil, gasoline, diesel fuel)
50% from cars and other motor vehicles
50% from factories, power plants and other sources.
Major Air Pollutants & their Effects
POLLUTANT EFFECTS
Carbon Monoxide illness, death
Nitrogen Dioxide breathing problems, lung damage
Sulfur Dioxide acid rain, breathing problems
Particulate Matter breathing problems, throat irritation
Ozone smog, asthma
How do youcontribute to air pollution?
OUR Impact on Air Quality…
The cup of water in front of you represents unpolluted, clean air.
You’ll add drops of food coloringto represent the different types of air pollutants caused by everyday activities.
4/25/2015
15
OUR Impact on Air Quality…
BLUE – pollutants from consumer products & paints
GREEN – pollutants from lawn, garden, and construction machinery
RED – pollutants from cars & trucks
YELLOW – pollutants from power plants & factories
OUR Impact on Air Quality…1) Look inside your cup. If the air pollution
around you were this visible, would you want to breathe the air?
2) Are there other sources of air pollution you might have contributed to?
3) What could you do to reduce the pollutants in the air?
4) What is the combined effect of each person’s pollution?
That’s a lot of info… Let’s look at 3 pollutants
in greater detail:Sulfur Dioxide
Particulate MatterOzone
Sulfur Dioxide causes acid rain… yikes!►Pollutants in the air combine with water in the
atmosphere and form acids.
►That acid gets in our rain/snow and falls back to earth, harming our lakes & ponds, and all the organisms that live there.
What is particulate matter?►Tiny particles of dust and smoke in the air.
►These particles make it
hard to breathe. (especially for older folks and young kids)
►These particles also cause haze and reduce visibility.
View of Chicago on 2 different days
(one clear, one hazy) Chicago - Summer 2000.
Clear Day : PM 2.5 < 5 µg/m3
Clear Day in Chicago, Summer 2000
Chicago - Summer 2000.Hazy Day : PM 2.5 = 35 µg/m3
Hazy Day in Chicago, Summer 2000Wait – isn’t OZONE a good thing?
►The ozone layer in the stratosphereprotects us. GOOD
►BUT ground-level ozone makes SMOG. BAD
(an UNHEALTHY brown haze)
Atlanta
Particulate Matter & Smog in Atlanta
4/25/2015
16
How can you protect yourself from air pollution?
• Check your local Air Quality Index (AQI) every day.
• The AQI is a color-coded system that tells you how clean the air is.
Good
Moderate
Unhealthy
for sensitive
groups
Unhealthy
Very
Unhealthy
Hazardous
What time of day has the worst air quality?
Interesting Air Pollution
Facts…
Air Pollution can travel far…
What goes around …comes around
Forest fire smoke
drifts across Florida
PM & CO2 drift from Asia to U.S.
Clouds
Smog
Air Pollution kills people…
Annual Deaths due to:
Air Pollution = 23,000
Drunk Driving = 17,000
Murder = 20,000
North Carolina summers are not good for your health!
In NC, air pollution causes an EXTRA:
240,000 Asthma Attacks
6,300 ER Visits
The “Worst 25” Cities for OzoneAtlanta 6th
Knoxville 8th
Charlotte 9th
Raleigh-Durham 13th
Nashville 18th
Memphis 19th
New York 20th
Birmingham 21st
Greensboro-Winston 21st
Macon 24th
Chattanooga 24th
Let’s take a closer look at particulate
matter…
4/25/2015
17
Airborne Junk1) In your science notebook, write the
following question:
What does particulate matter look like?
2) Examine the samples with the magnifying lenses and stereoscopes.
3) Draw what you see for 2 samples. Be sure to note where the samples came from…
Airborne JunkIn your science notebook, answer the conclusion questions:
1) Which locations had the most particulate matter?
2) Which locations had the least particulate matter?
3) Why would certain locations have more than others? EXPLAIN!
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