Unveiled in 1989, the new lighting arrangement required the removal of the contour-outlining light bulbs and the installation of 176 floodlights in and around the tower's frame. From dusk to midnight, the floodlights illuminate the entire tower. Sodium vapor lamps are used from 2 October to 6 July to cover the tower in an orange color. From 7 July to 1 October, the lights are changed to metal halide lamps to illuminate the tower with a white color. The reasoning behind the change is a seasonal one. Ishii reasoned that orange is a warmer color and helps to offset the cold winter months. Conversely, white is thought a cool color that helps during the hot summer months.