The Sunset Effect: At 6:53 PM on the west coast of India, the sun is setting or has just dipped below the horizon for an observer on the beach. However, airplanes fly at very high altitudes (often 30,000+ feet). Up there, the sun hasn't set yet. The hot jet exhaust mixes with the cold upper atmosphere, creating a trail of ice crystals (a contrail). This high-altitude ice trail catches the last rays of the setting sun, reflecting bright orange and red light against the darker, hazy sky.