Obviously, sunrise and sunset are mostly noted for the associated changes in the colour of the sky especially around the sun. On some occasions, clouds will also reveal different colour patterns if present around sunrise and sunset. It is very difficult to describe the various colour changes that occur with the different clouds around these times. But there are general stages that are associated with the times from dawn to sunrise and sunset to dusk. The heights of the clouds have an important influence on the length of times that cloud reflections occur. The higher the cloud, the longer the cloud bases will be able to reflect light. In fact, high clouds will reflect light for periods of up to 30 minutes whilst low clouds will typically reflect light from their bases for around 5 to 10 minutes. The reason for such a vast difference is that lower level clouds near the horizon are much closer to the observer around 1 to 15 kilometres away than clouds at higher levels which may be up to a few hundred kilometres away. The cloud bases of higher clouds therefore reflect light well before sunrise and remain so until just before sunrise. The same situation still applies for sunset but in the opposite order.
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