Noctilucent cloud season is upon us. If you’re in the Northern Hemisphere this summer, keep your head to the skies at sunset ...

Noctilucent clouds, Earth's highest clouds, shine blue in the twilight sky from late May to August in the northern hemisphere ...

Noctilucent clouds usually form close to the poles, but in recent decades, they’re being spotted closer to the Equator ...

The best time to see noctilucent clouds is on clear nights between late May and mid-August, about 90 to 120 minutes after ...

These are cumulus clouds. They resemble cotton balls and form when it's warm and humid," he said. Cappucci went on: "Because the sun is near the horizon—it's sunset—it's beneath the cloud.

Noctilucent clouds are rare high-altitude clouds visible only under certain conditions. They form during the summer months and appear after sunset as delicate, wispy blue or silver streaks across ...