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Electric Clouds This Summer

Climate change and rocket exhaust are seeding a light show in the northern skies.

The extreme low temperatures allow what water vapor exists to condense on dust and other particles, forming tiny ice crystals that scatter sunlight, giving the clouds their incandescent glow. SHADOW LINE: Noctilucent clouds can only be seen about an hour or two after sunset, or before sunrise—when the upper atmosphere is lit up by the sun’s rays, but the rest of the sky is dark enough to let their ethereal blue shimmer shine through. Observers initially thought they were caused by the Krakatoa eruption, but research conducted since then about whether ash and water vapor expelled by volcanoes can trigger the creation of noctilucent clouds has been inconclusive.

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