Selective yellow is a colour for automotive lamps. Under ECE regulations, headlamps were formerly permitted to be either white or selective yellow—in France, selective yellow was mandatory until 1993.
Both the internationalised European ECE Regulation 19 and North American SAE standard J583 permit selective yellow front fog lamps. ECE Regulation 48 currently requires new vehicles to be equipped with headlamps emitting white light. However, selective yellow headlamps remain permitted throughout Europe on vehicles already so equipped, as well as in non-European locales such as Japan and New Zealand.
The intent of selective yellow is to improve vision by removing short, blue to violet wavelengths from the projected light. These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow. Removing the blue-violet portion of a lamp's output to obtain selective yellow light can entail filter losses of around 15%, though the effect of this reduction is mitigated or countervailed by the increased visual acuity available with yellow rather than white light in bad weather.
Read more about Selective Yellow: Formal Definition
Famous quotes containing the words selective and/or yellow:
“The selective memory isn’t selective enough.”
—Blake Morrison (b. 1950)
“The prairies were dust. Day after day, summer after summer, the scorching winds blew the dust and the sun was brassy in a yellow sky. Crop after crop failed. Again and again the barren land must be mortgaged for taxes and food and next year’s seed. The agony of hope ended when there was not harvest and no more credit, no money to pay interest and taxes; the banker took the land. Then the bank failed.”
—Rose Wilder Lane (1886–1968)