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Why do you see your breath outside on a cold day? 🌬️

The process relies on the balance between the air temperature and dew point temperature

The process relies on the balance between the air temperature and dewpoint temperature

Chilly, festive-feeling air has returned to South Central Texas!

When temperatures turn cold, sometimes you can see your breath when holding a conversation or simply just breathing outside.

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So what exactly causes your breath to turn into a mini-cloud when you exhale? We dove into the science below:

The science

This process relies on just the right balance between the air temperature and the dew point temperature.

The human body contains nearly 70% water, so the air in our lungs largely consists of water vapor.

When you exhale a warm breath, the cold air outside quickly lowers the temperature of that breath, sometimes allowing it to reach the dew point.

Similar to how a cloud and fog forms, when the air temperature reaches the dewpoint temperature, that water vapor then condenses.

That process creates the small, brief cloud that we see when breathing outside in cold conditions.

So next time you are outside playing with the kiddos and see your breath, you’ll know the science behind why that happens!



About the Author
Mia Montgomery headshot

Meteorologist Mia Montgomery joined the KSAT Weather Authority Team in September 2022. As a Floresville native, Mia grew up in the San Antonio area and always knew that she wanted to return home. She previously worked as a meteorologist at KBTX in Bryan-College Station and is a fourth-generation Aggie.

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