1. What is Air? It’s a GAS! Mostly Nitrogen= 78% Oxygen = 21%
Argon = about 1%
Trace amounts of other gases
Since air is a gas, it is matter – which means it has mass and occupies space.
In the picture, you see the composition of Earth’s atmosphere ( 78% N2, 21% O2, 1% Ar, with trace amounts of elements in lower chart)
Photo:
Composition of Earth’s Atmosphere

2. Volume Define system Molar Volume of any gas at STP = 22.4 L
Contest - blow up balloon in bottle to show that air occupies space- one bottle has holes and one doesn’t
“Wilbur’s Space Machine” book
Put bead cases on viewer
Just because you learned that gases expand to fill their container, doesn’t mean that every bit of that space is occupied with a gas at any one time, lots of empty space
When determining the amount of a gas (blow up balloon), you have to define your system.
Are you looking at the entire atmosphere as a whole (As a whole, the atmosphere extends to at least 800 miles above the earth's surface.) or just small areas of the atmosphere (microclimate) or a closed system such as this balloon?
When comparing gaseous systems, we use a measurement called molar volume. The molar volume of any gas at Standard Temp and Pressure is 22.4 L
Pic -
Earth pic-

3. Amount of Gas 1 Molar Volume (22.4 L) =
6.02 x 1023 particles (Avogadro’s number)
1 Mole
Add beads to cases, we can count these particles.
How many particles are in this balloon? Since we can’t see them, counting would be difficult. An easier method would be to use the volume that we just discussed. A molar volume of any gas at STP is 22.4 L and this volume contains Avogadro’s number of particles. So, to determine the number of particles in this balloon, we could use water displacement to determine its volume and calculate the number of particles. In 5th grade, you wouldn’t have to do anything like that. The amounts of gas that you discuss will just be relative (more air or less air - release air from balloon). However, since kids ask all sorts of questions, I just want you to be prepared.

4. Pressure The force exerted by the weight of air molecules
Atmospheric pressure = 14.7 lbs/in2
Pressure –
Demo – can crush, newspaper and shims, Egg in bottle, air bag
Pic-

5. Behavior of Gases Parameters Definition Amount of gas
Number of particles, mass
Volume
Amount of space occupied
Temperature
Average kinetic energy of the particles
Pressure
Force exerted
To understand our atmosphere with its weather and climate changes, you have to first understand how gases behave.
In this portion of our workshop, we will develop some basic principles of Meteorology as we investigate the behavior of gases.
I’m also going to demo a model of gases that can be used in an inquiry fashion for student investigations.
There are 4 parameters that determine the behavior of gases:
- Amount of the gas – number of beads
- Volume – size of container
- Temperature - shaking
Pressure – collisions

6. Principles of Meteorology
Foldable
Envelope fold
Add information at each of 4 stations
Show how to do envelope fold with foldable
Pic-

7. Station 1 Temp vs. Volume Charles’ Law (closed system, constant P)
As temperature decreases, volume decreases
As the air cools it condenses.
Temp is a measure of avg KE. If temp decreases, less KE so particles are slowing down.
If they move around less, the take up less space.
Think of a hot crowded gym with kids sitting on bleachers, when its hot the kids are moving around more, don’t want anyone touching them sit farther apart.
Think of the same gym in the winter time, everyone is huddled together for warmth, not moving as much.
Charles’ law – if ideal gas in a closed container
Thermal expansion

8. Station 2 Temp Vs. Density
When temperature decreases, density increases
As cooler air condenses it becomes more dense and sinks forcing warmer air upwards.
In station 2 – how does temp relate to density? If you change volume, then density has to change since D = mass/volume.
In balloon from station 1, fixed amount of gas. As temp inc, volume inc, and as temp dec, volume dec.
Look at math and model density with beads and cases
Let’s say, when heated, we have 10 g in 100 mL of space D= 10/100 = 0.1g/ml
When cool, we have the same mass in less volume - 10 g in 50 mL of space D= 10/50 = 0.2 g/ml
So density increases
Model density
2 bead cases – different volumes but same number of beads

9. Station 3 Volume and Pressure
Boyle’s Law (closed system, constant T)
As volume increases, pressure decreases
As warm air rises, it expands (volume inc). As volume increases, pressure it exerts decreases
Warm fronts = low pressure
Cold fronts = high pressure
Boyle’s law - if ideal gas in a closed container
P & V vary inversely, as volume inc, P dec
Use model to explain:
Same number of particles = beads
Change volume – different size containers
Same temp/KE – shake at same rate
What happens to pressure (number of collisions)
(also higher density as in cold front, more pressure)

10. Station 4 – Pressure and Temperature
Gay-Lussac’s Law
As pressure decreases, temperature decreases
As the pressure of the rising air decreases, the air cools. The moisture in the air condenses to form clouds.
Gay-Lussac’s law – if ideal and in closed system
As pressure dec, temp dec
Model
Same number of particles or beads
Same volume – container size
Easier to look at effects of temp on pressure
Shake one gently and one hard – which exert more pressure? (high temp)
less P? (low T)

11. When 3 factors change… Combined Gas law P1V1 = P2V2 T1 T2
VOLUME increases (rising air)
PRESSURE decreases (Boyle’s Law)
TEMPERATURE decreases (Gay-Lussac’s Law)
Looks like charles’ law has been violated (volume inc and temp dec)
not a closed system either

12. Fronts
Carol – density flow model

13. Cold Front Forms cumulus clouds
Strong cold front forms cumulonimbus clouds, storms, tornado, snow squalls
Low humidity
Cold air mass advances toward warm air mass
Cold air mass slides under warm air mass
Forces warm air to rise and cool rapidly
Can produce rapid temperature drops and severe weather
Carol – density flow model
(add info?)

14. Warm Front Warm air advances toward cold air mass
Warm air slides over cold air
Front moves more slowly with a gentle rise in temperature
Produces less severe weather, steady precipitation lasting for days
Leading edge forms high cirrus clouds at first, then cirrostratus, altostratus, and nimbostratus later
High humidity
Carol – density flow model

15. Condensation
Cool air causes water VAPOR to condense - contains less moisture than warm air
Relative humidity - a measurement of the amount of water vapor in the atmosphere compared to the amount of moisture that can be in gas form at a given temperature.
Dew point - the temperature to which air would have to be cooled to become “saturated”. Once the air is cooled enough, the water vapor condenses to form a liquid.
ﾐ relative humidity lab
ﾐ water cycle model – book bringing the rain to kapiti plain - Draw phase changes
Warm air can hold more water vapor than cool air so the relative humidity is based on air temperature.

16. Rain and Clouds
What are other examples of water cycle – on large or smaller scale?
Lid with condensation on stove
Steam up mirror in bathroom

17. There is a fine line
Precipitation and cloud formation is all about states of matter
When water evaporates at the surface, it is an invisible gas.
As the water vapor (gas) rises, it cools and condenses to a liquid droplet. Clouds are liquid! (condensed water vapor)
Rain is larger droplets of liquid that fall to the ground.
States of matter depend on the energy of the molecules
Rain droplets are also round, not teardrop shaped

18. Careful explanation
Air does not “hold” water.
So what can we say:
Air is a mixture. Water vapor is commonly found in air. If the air is cold enough, water cannot remain in gas state and becomes liquid. The size of the drops and amount of water will determine if it can stay aloft or if the force of gravity is enough to pull the liquid to the ground.
This can perpetuate a misconception that gases are like solid sponges or liquid solutions. Gas mixtures do not behave like either of these scenarios.

19. Atmosphere Exosphere Ionosphere Thermosphere Mesosphere Stratosphere
Troposphere
Our atmosphere is composed of
Troposphere - weather
Stratosphere - Temperature increases with height - contains the ozone layer, the part of the Earth's atmosphere which contains relatively high concentrations of ozone.
Mesosphere - temperature decreases with height
Thermosphere - temperature increases with height.
Ionosphere- ionized by solar radiation - Influences radio propagation to distant places on the Earth. It is located in the thermosphere and is responsible for auroras.
Exosphere - particles are exchanged with magnetosphere or solar winds
Photo:

20. Atmosphere

21. Atmosphere Misconceptions: The atmosphere traps radiation.
The atmosphere “re-radiates” the radiation back to Earth.
The atmosphere works like a greenhouse, blanket or car.- NO!
True Statement-
Radiation is absorbed by the atmosphere and radiates back to the Earth.
Two times more heat comes from our atmosphere than the Sun.
The atmosphere promotes convection instead of preventing convection.

22. Misconception?

23. Weather Station Temperature Barometric pressure Relative humidity
Light
Anemometer
UVA/UVB