The Earth is a writhing, seething cauldron of molten rock and metal. In some spots under the Earth, the pressure builds and builds, until something has to give, and KABLAM! You get a huge volcanic eruption.
On the other hand, sometimes the pressure just gets relieved nicely and steadily and politely, like in the Klyuchevskaya volcano in Kamchatka, Russia, as seen in this gorgeous Terra satellite image:
It's a bit hard to tell here, but this is one teeny tiny part of a breathtakingly ginormous image that you can get by clicking the picture. Seriously, it's 6000 x 8500 pixels.
And it's stunning. This volcano, located in the far east side of Asia, erupts pretty steadily. That's actually a good thing, given that first scenario above. There are actually four erupting volcanoes in this area; another one, Bezymianny, can be seen just below the big one. In the original huge image, you can barely see either of them, but in this close crop you can see the plumes from both blowing to the northeast. And if you look carefully, you can even see a glowing red line indicating lava flows on Klyuchevskaya right at the peak. In the full size image you can actually see two such flows.
When I was a kid I loved space and volcanoes and dinosaurs. I used to draw giant Apatosauri (though we called 'em brontosauri back then) with big conic volcanoes in the background blowing out giant plumes. My scientific accuracy was probably somewhat dwarfed by my enthusiasm back then, but the cool thing is now, as a grown-up, I get to see pictures like this one! Maybe there are no dinosaurs in them, but there's still something incredibly cool about looking down on a volcano. And you can see the shadow of the plumes on the ground, too!
People joke about living in the future, but c'mon: we get satellite pictures of erupting volcanoes in full color and high-resolution delivered right to computers in our homes.
I love the future. Which is good, because I'll be spending the rest of my life there. You too.
Image credit: Jesse Allen and Robert Simmon, using data from the NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.
... or seriously, click the volcano tag under the pictures to see all the posts I've made about them!