As used in sections 307.020 to 307.120, unless the context requires another or different construction:

(1) “Approved” means approved by the director of revenue and when applied to lamps and other illuminating devices means that such lamps and devices must be in good working order;

(2) “Auxiliary lamp” means an additional lighting device on a motor vehicle used primarily to supplement the headlamps in providing general illumination ahead of a vehicle;

(3) “Headlamp” means a major lighting device capable of providing general illumination ahead of a vehicle;

(4) “Mounting height” means the distance from the center of the lamp to the surface on which the vehicle stands;

(5) “Multiple-beam headlamps” means headlamps or similar devices arranged so as to permit the driver of the vehicle to use one of two or more distributions of light on the road;

(6) “Reflector” means an approved device designed and used to give an indication by reflected light;

(7) “Single-beam headlamps” means headlamps or similar devices arranged so as to permit the driver of the vehicle to use but one distribution of light on the road;

(8) “Vehicle” means every device in, upon or by which a person or property is or may be transported upon a highway, excepting devices moved by human power or used exclusively upon stationary rails or tracks;

(9) “When lighted lamps are required” means at any time from a half-hour after sunset to a half-hour before sunrise and at any other time when there is not sufficient light to render clearly discernible persons and vehicles on the highway at a distance of five hundred feet ahead. Lighted lamps shall also be required any time the weather conditions require usage of the motor vehicle’s windshield wipers to operate the vehicle in a careful and prudent manner as defined in section 304.012. The provisions of this section shall be interpreted to require lighted lamps during periods of fog even if usage of the windshield wipers is not necessary to operate the vehicle in a careful and prudent manner.