Red, orange and pink clouds occur almost entirely at sunrise and sunset and are the result of the scattering of sunlight by the atmosphere. When the angle between the sun and the horizon is less than 10 percent, as it is just after sunrise or just prior to sunset, sunlight becomes too red due to refraction for any colours other than those with a reddish hue to be seen. ~Wikipedia
I used to live in a second-storey flat that faced east-west. This meant that we could view both sunrises and sunsets. The most spectacular sunsets were in the autumn months. I miss those skies.