Which factor is NOT considered when determining the autoignition temperature (AIT)?

The factor that is not considered when determining the autoignition temperature (AIT) is the color of the fuel. Autoignition temperature is primarily influenced by the physical and chemical properties of the fuel, such as its molecular structure and composition, which dictate how easily it can ignite in the presence of an ignition source.

In contrast, the type of fuel plays a significant role because different fuels have varying ignition characteristics based on their energy content, volatility, and combustion properties. Atmospheric pressure can also affect the AIT, as changes in pressure can alter the concentration of vapor and thus influence whether the fuel reaches its ignition point. Likewise, surrounding temperature has a direct impact on the thermal energy available to a fuel, which can facilitate or hinder the ignition process.

The color of the fuel, however, does not have any impact on the autoignition temperature, making it irrelevant in this context.