In the nineteenth century, Glasgow born physicist Lord William Kelvin produced what is now known as the Kelvin color temperature scale, which was based on his experiments using a black body emitter (a block of carbon). On heating, the black body produced a range of colors that he noted followed a definite progression.

The Kelvin scale assigns a numeric value in degrees Kelvin to each step of that progression, from black through red, orange, white, and then beyond that into the blue area of the color spectrum. Over the years, this scale has become so much a part of the standards and terminology used in disciplines such as photography, stage and film lighting, and now the creation of digital imagery, that anyone who wants to work in these industries really needs to understand at least the basics of the Kelvin scale and how it is used.

Often, you will hear a particular light type or maybe a lighting setup being referred to as being warm or cool in nature. This temperature...