Noctilucent clouds are rare high-altitude clouds that can only be ... the highest increase in noctilucent cloud frequency in 15 years. So why the sudden increase? The emerging theory is that ...

Noctilucent clouds, silvery-blue tendrils ... scientists have recorded more frequent appearances than any time in the past 15 years, according to NASA, which studies the mysterious clouds with ...

Noctilucent clouds are collections of ice crystals that linger high up in the mesosphere ... activity–the biggest spike in 15 years. If this continues, NLCs could be easy to see over the ...

DULUTH — Recently, I had the opportunity the see a couple displays of noctilucent clouds. Now that we're approaching the summer solstice, this is "high season ... In recent years, NLCs seem ...

These are noctilucent or “night-shining” clouds made up of tiny grains of ice, about the size of a flu virus (100 nanometers). They are formed in the upper reaches of the mesosphere.

Rare noctilucent clouds that glow in the dark are currently lighting up much of the northern hemisphere — and the recent display is the most vibrant in 15 years. The wispy ghost-like clouds ...

Researchers say the blast may temporarily warm surface temperatures in years to come and also deplete stratospheric ozone. On Jan. 15, the underwater ... steam and ash 36 miles high, probably ...