Transcript INVESTIGATION 5

Water in the Air
Condensation, Clouds, Precipitation
Investigation 6
Pressure / Temperature
Demonstration
• What happens to
the temperature of a
gas if you squeeze
it into a smaller
volume?
• Pressure/Temperature
Demonstration
worksheet
Soda Bottle Demo #1
1. Resting temperature
2. Apply pressure to the
bottle and hold it
3. Observe the temperature
4. Release the pressure and
observe the temperature
Soda Bottle Demo #2
1. Starting temperature
2. Pump the cap 40 times or
more as you watch the
temperature
3. Observe the pressure
4. Release the pressure and
observe the temperature
Results
Squeezed by
Hand Bottle
Soda-bottle Pump
Bottle
Volume


Pressure


Temperature


(added air molecules)
What happened…
•
When we released the pressure
–
Temperature decreased
Questions
• Answer questions 2, 3 and 4 on the
Pressure/Temperature Demonstration
worksheet
Question 2 Answer
2. Decreasing the volume causes the
molecules to move faster with the greater
pressure, increasing the temperature
V  = MM  = P  = T 
Question 3 Answer
3. Squeezed the sides of the bottle = decreased the
space = pushed down on the plunger.
The number of air molecules stayed the same in
a smaller space = increase pressure, increased
temperature
V  = MM  = P  = T 
Question 4 Answer
4. Temperature must go up in the syringe because
the pressure goes up
V  = MM  = P  = T 
Summarize
Force smaller
volume
1. Gas molecules
are forced closer
2. More collision
occur
3. Increase in
temperature and
pressure
Summarize
Increase the
volume
1. Gas molecules
spread out
2. Less collision
occur
3. Decrease in
temperature and
pressure
Cloud Formation
•
•
•
•
•
•
•
•
Have you seen any clouds lately?
What did they look like?
Where are clouds?
Are they always in the same place?
What is a cloud?
What is it made of?
Where do clouds come from?
How do you think they form?
2 Types of Clouds
• Clouds appear as one of these 2 basic types…
• Stratiform– clouds that are flat and
layered. These form when weather is
stable. They are the result of a large, moist
air mass being lifted.
• Cumuliform—puffy, fast-moving, and
rapidly growing clouds.
Clouds are classified by height
Cloud Word Orgins
•
•
•
•
•
Cumulus- Latin – “heap”
Stratus – Latin – “layer”
Nimbus – Latin – “rain-bearing”
Cirro- “high”
Alto- “middle”
High
• Clouds forming above 5000 meters have cirro- prefix and
since the temperatures are so cold at such high elevations,
these clouds are primarily composed of ice crystals.
• These clouds are thin and wispy, blown by high winds into
long streamers. They are typically thin and white in
appearance, but can appear in a magnificent array of colors
when the sun is low on the horizon.
• Cirrus
• Cirrocumulus
• Cirrostratus
Middle
• Clouds that form between 2000-5000 m are
given names that begin with the alto- prefix.
• Nimbostratus
• Altostratus
• Altocumulus
Low
• Low level clouds form below 2000 meters.
(no special prefix)
-Stratus
-Stratocumulus
-Cumulus
-Cumulonimbus
Cloud in a Bottle?
• Using a 2-liter soda bottle, containing 25
mL of water
• Water vapor into the air?
– Shaking the bottle
– Warming the water
Shake, shake, shake
• Have we formed a cloud yet?
• NOT YET
Cloud recipe
• Saturate the air with water vapor
– Shake the bottle
– Warm the bottle by holding it in your hands
– Increase the pressure to increase the
temperature
• Then
– Release the pressure on the bottom to decrease
the temperature (to get the water vapor to
condense - dew point)
Did it Work?
• NOT YET!
• There is a piece missing
• There is nothing for the water droplets to
form on!!
What’s Happening?
You start off with
some water in the
bottle and some
smoke.
When the bottle is
compressed the
air gets hotter so
the water
evaporates.
When you let it
expand the water
condenses on the
smoke particles
forming a cloud.
Condensation Nucleus
• Clouds are composed of tiny droplets of
condense liquid water
• Water vapor is condensing on the particles
of smoke and the plastic of the bottle
• The particle on which water vapor
condenses in the air to form a cloud
Is This How Real Clouds Form?
The process is very similar to how clouds from on a sunny
day. Warm moist air rises, and as it rises there is less air
above it so the pressure reduces.
In Real Clouds
• What would be the condensation nuclei in
the outside air?
–
–
–
–
–
–
Dust
Smog
Air pollution
Smoke
Salt
Chemicals
How do Clouds Form?
Precipitation
• Water that falls from the sky
• Kinds of precipitation
–
–
–
–
Rain
Snow
Sleet
Hail
Raindrops and Cloud Droplets
• Measure the average diameters
• Comparison of size - page 80 in the
Resource Book
Measuring Precipitation
• Most important weather factors monitored
• Measured with a rain gauge
Fog Forming on Land
Don’t forget to use the
helpful website links on
Science page
for additional
information