What is the process called when experiencing a chill near a cold wall?

The phenomenon of feeling a chill near a cold wall is primarily attributed to radiation. When an object, such as a wall, is much colder than the air in its immediate environment, it emits infrared radiation. This radiation can be absorbed by nearby objects, including the human body, leading to the sensation of chilliness. While convection and conduction can also play roles in heat transfer, the sensation near a cold wall is predominantly due to the radiation emitted from that surface.

Radiation does not require a medium to transfer heat; it can take place through a vacuum, which is why even when you're not in direct physical contact with a cold surface, you can still feel the effects of its temperature on your body. As the colder wall radiates heat away from your body, you lose body heat to the wall, which manifests as a feeling of chilliness.