Why You Can See Your Breath
Written by Studio AM.
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On many cold days, you can see a small white puff when you breathe out. The water in your breath explains why.
Air from your lungs contains water vapor, which is water in its gas form. This vapor is invisible. It is not the white cloud you see.
When your warm breath mixes with colder air, it cools. If it cools enough, some of the vapor changes into liquid water. The water gathers into tiny drops that scatter light, making the puff visible. This change from gas to liquid is called condensation.
Clouds also contain tiny water drops, and some contain ice crystals. Drops can form as moist air rises and cools. A visible breath gives you a small example of condensation close to home.
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Questions
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Question 1 of 4
What is the main point of the passage?
The answer is A: Cooling can turn water vapor in your breath into visible tiny drops.
The passage explains the change from invisible vapor to drops that scatter light.
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Question 2 of 4
Why might your breath remain invisible in warmer air?
The answer is C: It may not cool enough for visible drops to form.
The passage says sufficient cooling is needed for some vapor to become liquid drops.
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Question 3 of 4
In this passage, "gathers" means
The answer is D: comes together in one place
The water comes together to form tiny drops.
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Question 4 of 4
According to the passage, why does the puff of breath look white?
The answer is B: The tiny water drops scatter light.
The third paragraph connects light scattered by drops with the visible puff.
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