Hands down Jupiter’s got the most the bizarre clouds in the solar system. All those swirls, whirls and vortices look like so much cream in a cup of coffee. If you’d asked Van Gogh to paint Jupiter sight unseen, I’m sure it would bear a remarkable resemblance to the real thing. Clouds form on Jupiter the same way they do on Earth only it’s much colder there because the planet is five times farther from the sun.
In Jupiter’s upper atmosphere, crystals of ammonia ice condense to form the cloud deck we see through our telescopes. Deeper down, clouds combining ammonia and hydrogen sulfide (a smelly, dangerous gas) dominate, while several hundred miles below that, where temperatures are warmer, clouds are composed of familiar water vapor.
Jupiter rightfully gets a lot of attention for its clouds, and the latest Juno photos reveal them in incredible detail, each image more amazing than the next. But I’d like to also through in a vote for Earth, a planet with lots of weather and one where you can see amazing clouds without the need for a telescope — or a clear night!
If you regularly look up, there’s a cloud feast up there. Some are rare but many common forms can take on a special beauty depending on time of days, upper atmospheric winds and what a particular cloud might be doing right now over your house or apartment. Variations in textures and forms can sometimes last just minutes, so take the time to admire nature’s evanescence.
If a thunderstorm is forecast be on the alert for the Jupiter-like whorls of squall line clouds. Close examination of squall lines will often reveal rotation in the clouds from high winds.
We’ve talked about halos here many times. They’re formed by light refracted by pencil-shaped, six-sided ice crystals in high clouds. The most common halos have a radius — the distance from the sun to the edge — of 22° or two side-by-side fists held against the sky. Rarely, halos of different diameter called “odd radius” halos can appear when light is refracted by pyramidal crystals. This past Friday afternoon the normal 22° halo looked unusually soft and bloated. At the same time I noticed fainter inner arcs that I could trace partway around the sun — baby halos with radii of 18° and 9°!
Then on Saturday (June 22), while stopped at a gas station, a raft of cirrocumulus clouds shaped like a bird of prey approached the sun from the west. When I pointed out the cloud to another person standing by the first words out of his mouth were “the UFOs are coming.” Cirrocumulus are a high altitude version of the familiar cauliflower-shaped summertime cumulus. They form from 3 to 7 miles high and look like narrow, wavy bands made of tiny clouds puffs. Sometimes the higher ones can look smooth at first and then develop into narrow, gill-like rows right before your eyes.
Cirrocumulus are transitional clouds in a weather front pattern and generally don’t last long. These hung around for about 45 minutes before spreading and evaporating away. Ah, life is too brief.
I have many favorites would argue that Earth has cloud skills to rival the solar system’s biggest planet. That said, here are a few other spectacular types you might see at any time. If you’d like to learn more about clouds, here’s a simple guide. To learn more I highly recommend the World Meteorological Association’s International Cloud Atlas. They also have an extensive photo gallery useful for identifying clouds you’re not sure of.
I usually finish with a “clear skies!” but this time I wish you clouds 🙂