Aluminum feels colder than the current ambient temperature due to its high thermal conductivity. Thermal conductivity refers to the ability of a material to conduct heat. Aluminum has a relatively high thermal conductivity compared to many other common materials, such as wood or plastic.
When you touch an object, heat is transferred from your skin to the object or vice versa depending on their relative temperatures. In the case of aluminum, it conducts heat away from your skin more efficiently than the surrounding air or other materials commonly encountered in daily life.
When you touch aluminum, it rapidly conducts the heat away from your skin, causing your skin to lose heat. This transfer of heat creates the sensation of coldness. Since aluminum conducts heat better than the air, it feels colder than the ambient temperature. In reality, the aluminum itself is not colder; it simply conducts heat away from your skin more effectively, giving the perception of being colder.
It's worth noting that different materials have different thermal conductivities, and the sensation of coldness can vary depending on the specific material and its thermal properties.