Definition - What does Atmospheric mean?
Atmospheric is a descriptive word used to convey the state of the mixture of gases (including nitrogen, oxygen, carbon dioxide, argon and a range of noble gases) existing in free space. Atmospheric conditions include temperature, air pressure and humidity.
Corrosionpedia explains Atmospheric
The atmosphere contains moisture, which creates an electrochemically reactive environment that facilitates corrosion reactions and oxidation. Atmospheric corrosion is a type of corrosion that is experienced by metals that are exposed to the atmosphere.