What Makes The Sky Colour? – Short Answer
Most of the time, the sky appears blue. This is because the different colours of white sunlight are scattered by gases in the atmosphere and the blue component is reflected back to the earth. During the setting of sun the sky appears red because the sunlight bounces off dust particles that hang steadily in the air. A red sky at dawn is caused by sunlight reflected from water droplets, indicating that it is going to rain that day.