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Name: Abby
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Last night, right after a heavy rain, A fog formed by the river and we could see our breathe in the air. There was also a 'fog' coming off a sweaty jogger? What was the cause of this?


The relative humidity of the air must have been very nearly 100%. This is quite likely, as you say that there had just been a heavy rain.

Any addition of water to the air (such as from evaporation from the river, your breath, or evaporation off of the sweaty runner) would saturate the air and cause "fog" to form.

David R. Cook
Climate Research Section
Environmental Science Division
Argonne National Laboratory

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