High-level couds such as cirrus, cirrocumulus and cirrostratus catch the red sunlight long after sunset, sometimes up to 10-20 minutes after sunset (or before sunrise), depending on latitude. Cirriform clouds will usually not show the twilight colors very intensely since for that, the sky should be exceptionally clear (which is usually isn't if the clouds are there). Cirriform clouds usually show a pale orange, red or purple.
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