Update, Monday


Colorful clouds in Rock Springs, near Cima, Calif., March 26 at 7:41 p.m. (Jim Cody)

If you read the article below on Friday, you’ll remember we mentioned the jury still being out as to the exact cause of the colorful cloud formation. We think we finally have an answer!

We mentioned rocket launches from nearby Vandenberg Air Force Base in Southern California were a possible cause, but there was no information revealing that any rocket or missile launches had gone off earlier in the week. However, a Navy news release from Thursday evening revealed there was, in fact, a successful test flight of two Trident II D5 missiles on March 26, the same evening the photo was taken. The missiles were launched from the Pacific Test Range off the coast of Southern California.

These ethereal cloud formations can form from rocket or missile launches thanks to the propellant and liquid oxygen released by the engines. This trail of exhaust left behind quickly freezes in the colder temperatures aloft, aided by calm conditions. The result is something similar to a contrail made of ice crystals, such that when sunlight or moonlight interacts with said ice crystals, a beautiful array of colors becomes visible in the sky.

Original post from March 30


Possible noctilucent clouds shimmer over Quartzsite, Ariz. (David Laucks)

Folks in western Arizona were caught breathless by these ethereal clouds shimmering over Quartzsite this week. Some thought the formation was residue left over from a rocket launch from nearby Vandenberg Air Force Base in California, but there were no rocket launches that night.

The only explanation is some sort of cloud formation.

At first glance, it looks a lot like cloud iridescence. That’s a common meteorological phenomenon that occurs when sunlight or moonlight passes through the liquid water droplets in the cloud, producing a pastel rainbow appearance, very similar to the process of how rainbows form. Often, the appearance of cloud iridescence is compared to oil films in water.

Cloud iridescence is one theory.

What caught my eye, and the eyes of several other meteorologists, was the idea that these could be noctilucent clouds, instead. Noctilucent clouds are rare already, and that they were seen in a southern latitude makes this an exceptional capture!

Latin for “night shining,” noctilucent clouds are made of ice crystals that are located very high in the atmosphere; they are visible only in deep twilight.

Noctilucent clouds are the highest clouds in Earth’s atmosphere, located in the mesosphere about 50 miles above the surface. The colors occur when sunlight passes through the ice crystals, similar to how sun dogs or halos form. However, the colors associated with noctilucent clouds are typically more faint than sun dogs because of the very small and thin nature to the moisture-starved ice crystals that high in the atmosphere. In fact, the mesosphere contains very little moisture — just a tiny fraction of the level of moisture in the air in the Sahara.

According to EarthSky, there’s a very narrow window to see them:

Noctilucent clouds are primarily visible when the sun is just below the horizon, say, from about 90 minutes to about two hours after sunset or before sunrise. At such times, when the sun is below the ground horizon but visible from the high altitude of noctilucent clouds, sunlight illuminates these clouds, causing them to glow in the dark night sky.

While they are most common between 50 and 70 degrees north latitude, they have been seen as far south as Denver and Orlando. They are most commonly seen during late spring and summer, and historical observations reveal they have been recorded more frequently across the Northern Hemisphere than the Southern Hemisphere.

Noctilucent clouds are not fully understood by scientists, with NASA and others doing research to get a better grasp on how these form.

Events such as rocket launches, reentry of space vehicles and explosive volcanic eruptions have been postulated as possible contributors to the formation of these elegant, practically out-of-this-world meteorological phenomena.

The jury is still out on whether this cloud formation captured by David Laucks was in fact noctilucent or simply the more common cloud iridescence.

Weather is awesome. #cwgpicoftheweek