Nacreous Clouds over Sweden
10.01.2020

Vivid and lustrous, wafting iridescent waves of color filled this mountain and skyscape near Tanndalen, Sweden on January 3. Known as nacreous clouds or mother-of-pearl clouds, they are rare. This northern winter season they have been making unforgettable appearances at high latitudes, though.

Iridescent Clouds over Sweden
15.01.2020

Why would these clouds multi-colored? A relatively rare phenomenon in clouds known as iridescence can bring up unusual colors vividly or even a whole spectrum of colors simultaneously. These polar stratospheric clouds clouds, also known as nacreous and mother-of-pearl clouds, are formed of small water droplets of nearly uniform size.

A Circumhorizontal Arc Over Ohio
19.05.2019

Why would clouds appear to be different colors? The reason here is that ice crystals in distant cirrus clouds are acting like little floating prisms. Sometimes known as a fire rainbow for its flame-like appearance, a circumhorizon arc lies parallel to the horizon.

A Heart Shaped Lenticular Cloud
14.02.2016

Can a cloud love a mountain? Perhaps not, but on a Valentine's Day like today, one might be prone to seeing heart-shaped symbols where they don't actually exist. A fleeting pareidolia, the featured heart was really a lenticular cloud that appeared one morning last July above Mount Cook National Park in New Zealand.

Mammatus Clouds Over Saskatchewan
18.10.2015

Why is this cloud so bubbly? Normally, cloud bottoms are flat. The flatness is caused by moist warm air that rises and cools and so condenses into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow, an opaque cloud forms.

Aurora over Clouds
24.11.2015

Auroras usually occur high above the clouds. The auroral glow is created when fast-moving particles ejected from the Sun impact the Earth's magnetosphere, from which charged particles spiral along the Earth's magnetic field to strike atoms and molecules high in the Earth's atmosphere.

Asperatus Clouds Over New Zealand
27.02.2013

What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Known informally...

As Above, So Below
3.12.2011

A single, long exposure captured these star trails above a remarkably colorful sea of clouds. As seen from Medvednica mountain, the surrounding peaks and lights illuminating the clouds from below are north of Zagreb, Croatia.

Jupiter Rotation Movie from Pic du Midi
6.12.2011

Observe the graceful twirl of the Solar System's largest planet. Many interesting features of Jupiter's enigmatic atmosphere, including dark bands and light zones, can be followed in detail. A careful inspection will reveal that central clouds rotate slightly faster than clouds toward the poles.

Noctilucent Clouds over Moscow
27.06.2013

This panoramic night scene from June 8 looks out across a Moscow skyline from atop the main building of Lomonosov Moscow State University. Shining in the darkened sky above are widespread noctilucent clouds. From...