system
Given the following post, respond as if you're commenting on Reddit:
human
Why is static always black and white even on color TVs?
gpt
It’s because of the way color was added to the original U.S. TV standard. (I’m assuming you are referring to the now-obsolete analog system; it obviously doesn’t work like this in the current digital systems.)

 Color TV had to be made compatible with the original black-and-white system. 

 Color TV signals are a little bit different than black-and-white TV signals - a certain frequency band within the signal is used to transmit color information. That band corresponds to high frequency horizontal detail (patterns about 1/200th of the width of the screen). In a Color TV signal, those details are elided and the information used to carry hue and saturation information instead. 

 This meant that Color TVs had to be able to correctly display a black and white transmission, one in which no color information was present. The way this was achieved was the addition of a “color killer” circuit, which detected the signals that indicated a color TV transmission and forced the set to behave as a black-and-white receiver when those signals (specifically, the “color burst” signal, which is a brief burst of the color sub-carrier frequency transmitted during the horizontal blanking period) weren’t present.

 Having a signal of the correct frequency at the correct time for that period of time is extremely unlikely to occur by chance (and even if it did, it would disappear again before you had the chance to notice it). So when the TV is showing static, it thinks it's showing an old black-and-white movie and turns off the color interpretation circuitry, leading to black-and-white static. 

 Of course, if you’re not tuned into ANY signal, those color signals aren’t present, so even”static” looks just like it would on a black-and-white set. Later, the dominant European system (PAL) would behave in a very similar manner.