Cloud Formation Lab Scenario: You are a scientist from the year

Cloud Formation Lab Class Copy – Use pages 88 - 89 of your science notebook!
Cloud Formation Lab
Scenario:
You are a scientist from the year 1642 and you are studying how and why different types
of weather occur as well as how clouds form. In your latest experiments, you have been
trying to create a cloud in a contained environment. To achieve this, you will be using
hot water, an Erlenmeyer flask, matches, and ice. What you will do is pour hot water into
the flask. Then, pour most of it out, light a match and put it in the flask, then cover the
opening of the flask. When that is done, you will put ice on the cover and observe what
happens inside the flask.
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Write a Testable Question and Hypothesis on page 88 of your science notebook.
Background Information:
Cloud formation in the troposphere happens as a result of many factors. First, the
earth is heated up by the sun through radiation. As a result of the sun heating the earth,
water evaporates, air heats up and rises in some areas and cools and sinks in others, high
and low pressure areas develop, and the air around the world moves. One consequence in
all if this is the formation of clouds.
Clouds need three general things to form in the atmosphere: 1) Uplift, 2)
Condensation, and 3) Low Pressure. Uplift refers to the movement of air upwards.
The air near the surface of the earth is warmer than the air in the upper troposphere.
Think about it, as you climb higher up a mountain the air gets cooler. When warm air
near the surface travels upwards, it cools. Water that is evaporated in the air can now
condense as a result of the cooler temperatures.
This leads to the second requirement for cloud formation, condensation.
Remember that condensation is when water changes from a gas to a liquid. For this to
happen, a water molecule needs something to stick to. When you take a hot shower for
example, the water vapor in the air condenses and sticks to the bathroom mirror.
Likewise, in the upper troposphere there are small particles of dirt, dust, salts, smoke, etc.
The cooled water vapor in the atmosphere condenses and sticks to these particles which
are called cloud condensation nuclei. When many of these condensed water molecules
are together in the air we see clouds.
The third requirement for cloud formation is low pressure. Think back to the
cloud in a bottle demonstration. When the bottle was squeezed, the cloud inside
disappeared. This represents a high pressure situation. High pressure helps water
molecules evaporate. Likewise, when the bottle was not being squeezed, the cloud could
be observed. Under the lower pressure conditions, the water molecules were able to
condense and stick to the smoke particles from the match. Thus a cloud formed.
Cloud Formation Lab Class Copy – Use pages 88 - 89 of your science notebook!
Cloud Formation Lab – Materials:
Erlenmeyer Flask
Safety glasses
Ice
Matches
Hot water
Watch glass
Cloud Formation Procedure:
Part 1:
1. Fill an Erlenmeyer flask with hot water.
2. Pour out most of the water, leaving about 3 cm at the bottom. Caution: Avoid
spilling hot water. Do not use water that is so hot that you cannot safely hold the
bottle.
3. Put a watch glass on the top of the water flask. Do not pick up the watch glass or
your results may be altered.
4. Place an ice cube on the watch glass.
5. Observe what happens inside.
Part 2:
1. Fill an Erlenmeyer flask with hot water.
2. Pour out most of the water, leaving about 3 cm at the bottom. Caution: Avoid
spilling hot water. Do not use water that is so hot that you cannot safely hold the
bottle.
3. Strike a match and drop the burning match into the bottle. Immediately cover the
mouth of the bottle with a watch glass. Do not pick up the watch glass or your
results may be altered.
4. Place an ice cube on the watch glass.
5. Observe what happens inside.
Data Table: Make in your science notebook. (page 88)
Trial
Observations
Control – No
Smoke Particles
Variable – Smoke
Particles
Questions/Conclusions: Answer the following in your science notebook on page 88.
1. In which part of the experiment did you observe the best cloud, Part 1 or Part 2?
2. Why did that trial form a better cloud?
3. How does pressure affect cloud formation?
4. What is the most important thing you learned about cloud formation?
5. If there were low air pressure in the atmosphere around the St. Paul ecosystem,
what kind of weather would you expect?
Cloud Formation Lab Class Copy – Use pages 88 - 89 of your science notebook!
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