Clouds at night are typically black or grey. This is because the luminance of clouds at night is usually too weak for our eyes to perceive color. However, exceptions exist.
Factors Affecting Cloud Color at Night
Several factors influence the apparent color of clouds at night:
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Moonlight: Clouds illuminated by the moon appear whitish. The intensity of this whiteness depends on the moon's phase and cloud density. Brighter moonlight results in brighter clouds.
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Artificial Light Sources: City lights and other artificial sources can cast colored light onto clouds, making them appear differently colored depending on the light source's color. This is why you might sometimes see a reddish or orange hue.
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Atmospheric Conditions: Scattering of light within the atmosphere can affect the perception of cloud color. Although less impactful at night than during the day, subtle effects can still occur.
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Noctilucent Clouds: A rare exception are noctilucent clouds, which are high-altitude clouds visible only during twilight. They appear silvery or bluish white due to their high altitude and interaction with sunlight below the horizon.
Examples
- A dark, moonless night will typically show clouds as dark grey or black.
- A night with a full moon will display clouds as a lighter grey or even whitish in appearance.
- Urban areas with significant light pollution might show clouds with subtle color casts from the artificial lighting.
The provided references confirm that generally, clouds at night appear black to grey unless illuminated by the moon or other light sources. While some instances mention other colors (like reddish-orange or pink), these are likely due to specific lighting conditions rather than the clouds’ inherent color.
