March - cumulus You are here: Home Photo gallery Atmospheric optics Light scattering Solar rays


Solar rays are also known as sunrays or cloud rays. In folklore the effect is called "the sun drawing water". Solar rays can be seen when sunlight passes past sharply defined clouds (like cumulus clouds) when the atmosphere is slightly dusty or hazy. Light is scattered by the aerosols and the light paths past the clouds become visible. In fact, it is often the shadow rays near the clouds which are remarkable, rather than the light solar rays themselves. Solar rays are all parallel to eachother, but perspective causes the apparent divergence from the sun.

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Observing tips

Solar and antisolar rays are caused by light scattering, and so there should be plenty of aerosols in the air (i.e. the air must not be too crystal clear). A slightly hazy sky makes for good opportunities to see these rays.

The rays are more distinct when the clouds covering some parts of the sky have clearly defined edges, like cumulus clouds. They may even be visible after sunset or before sunrise, when the clouds casting the shadows are so far away that they are below the horizon. The rays can then be seen shooting out of the horizon in the twilight arch (the band with twilight coloring).

Solar rays are easy to photograph, but make sure that the sun is not in the image when doing light metering, or the photo will be underexposed. Usually the sun is blocked by the clouds creating the rays anyhow.

Another opportunity to see these rays is in summer, when the sky is overcast with altocumulus floccus clouds; the moist atmosphere and the high cloud layer can create extensive solar rays.