Mammatocumulus

Photo credit - Euclid vanderKroew - cc-by-nc-sa

Photo credit – Euclid vanderKroew – cc-by-nc-sa

Mammatocumulus are impressive clouds. They are described as eerie, even foreboding. When you see them you get the feeling that something powerful is behind them, that something is going to happen. It’s true. Something powerful is there.

Mammatocumulus are associated with cumulonimbus, the most powerful of clouds. These are the thunderclouds, the ones that go boiling up, growing to great heights, getting so thick that sunlight can’t get down to their black bases. When they get so tall that they can’t grow any more, the wind up there blows their tops sideways, into the anvil characteristic of their cloud type. Once clear of the column of rising air, the saturated air in the anvil sinks. When there is enough moisture in this cold, sinking air to outlast the heating that results, clouds form in the lower atmosphere. pushing down into those ominous bulges. Mammatocumulus is a rare cloud that forms in sinking air rather than rising air. What gives mammatocumulus those well defined pouches is the air rising back up in the interstices between them.

Anvil cloud - Credit - Sfortis - cc-by-sa

Anvil cloud – Credit – Sfortis – cc-by-sa

There is definitely precipitation associated with mammatocumulus, though it comes not from them so much as from the cumulonimbus accompanying them. Along with the lightning and thunder and downdrafts and other severe weather. And finally, yes, mammatocumulus are so named because of their appearance.

rjb

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Webby Awards

Webby Awards logo

Webby Awards logo

The Webby Awards were established in 1996, when most people were, at best, just becoming aware of the Worldwide Web. The Webby Awards are presented annually by the International Academy of Digital Arts and Sciences. The Academy includes among its membership Kevin Spacey, David Bowie, Vint Cerf and Lawrence Lessig. Most people have heard of the first two, but fewer would know the other two. Briefly, Doctor Vinton Cerf is one of the pioneers who brought the Internet into being, giving the Worldwide Web a place to live. And Doctor Lawrence Lessig, among his other achievements, co-founded the Creative Commons.

Lawrence Lessig - Photo credit Joi Ito - CC-BY

Lawrence Lessig – Photo credit Joi Ito – CC-BY

Lawrence Lessig is receiving a Webby Award this year (Monday, May 19, 2014.) It is a lifetime achievement award for, to quote the announcement, “. . . his groundbreaking work as cofounder of Creative Commons. Creativity based on collaboration is absolutely fundamental to everything that makes the Web successful and wonderful – but none of that would be possible without the ability (and encouragement) to share, mix, and match creative works.” As usual, Opensource.com has an excellent article on this. If you’re interested in a deeper understanding of Lessig’s thinking on copyright and Creative Commons, here is an annotated speech he made this year. Warning: it’s about 45 minutes, so get comfortable.-)

Lawrence Lessig is also involved in the politics of his native country, the United States. His causes support increased openness and fairness. This one, which aims to expose and democratize political campaign funding, is interesting and audacious.

A man to be admired, but today we’re talking about the Webby Awards. So congratulations Lawrence Lessig on your Lifetime Achievement Award at this quarter century mark for the Worldwide Web.

rjb

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Virga

Photo credit - Quasipalm - Public domain

Photo credit – Quasipalm – Public domain

Cloud of the Day – Virga

Virga is not really a cloud. It’s a form of precipitation. But it’s not exactly precipitation in the normal sense, either. Virga is precipitation that falls out of a cloud but doesn’t reach the ground. Can you call it rain if it doesn’t make anything wet?

Photo credit - Simon A Eugster CC-BY-SA - Bidgee CC-BY

Photo credit – Simon A Eugster CC-BY-SA / Bidgee CC-BY

Virga doesn’t get its name as you’d expect. It’s not because it is virgin precipitation that doesn’t consummate its existence by touching the Earth. Virga has its root in Latin for “branch” or “twig.” I suppose it does kind of look as if the cloud has sprouted branches. I guess. If you hold your mouth right. Still, I like the other, more poetical, meaning better.

Photo credit - David Kibble / David Foxx

Photo credit – David Kibble / David Foxx

Virga happens when there is enough moisture in the air to form a cloud, and enough to form ice crystals or water droplets that are heavy enough to fall. Then, either because the air is too dry or too warm closer to the ground, the precipitation sublimates* or evaporates on its way down. These conditions prevail in dry areas, so virga is often seen in deserts or prairies.

Yes, there is precipitation, but you won’t need your umbrella.

*phase transition from solid to gas with no liquid phase.

rjb

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