Saturday, September 1, 2012
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Redwood Tree, California
Redwood Tree, California
Partway up a 350-foot tree, botanist Marie Antoine (at right) passes a slender core sample of its wood—750 years of redwood biography—to canopy ecologist Giacomo Renzullo. Research now shows that the older such trees get, the more wood they put on.
The California trees people call "redwoods" are actually two distinct species, both of them best described in superlatives.
Sometimes called simply the "big trees," giant sequoias (sequoiadendron giganteum) grow only in California's Sierra Nevada Mountains toward the state's eastern border. The most massive living things, they can reach 280 feet tall and 23 feet across. The largest rise a little over 300 feet and spread almost 30 feet across. The oldest have been around over 3,000 years.
Coastal redwoods (sequoia sempervirens) are the tallest living things on on our planet, growing 300-350 feet tall and 16-18 feet across, with record specimens soaring 360 feet. They are the primary tree in the redwood forests that grow from near the California coast from the northern border down to Big Sur.
Redwood forests are so plentiful in California that you'll find almost a dozen parks with "redwood" in their name, along with a national park and quite a few regional ones. Any of them will give you a glimpse of the magnificent trees and the forests they grow in, but we think the redwood forests listed below are some of the best places to see them. They're listed in geographic order from north to south.
Tiny Bubbles Explain Puzzle about Light from Sound
Sonoluminescence¿the physical phenomenon by which sound turns into light¿is as mystifying as a magic trick.
Despite 70 years of trying, scientists still cannot fully explain how a bubble of air in water focuses acoustic energy a trillionfold to spit out picosecond bursts of ultraviolet radiation. Initially physicists attributed the flashes to friction. In the late 1980s, though, they came to see that bubbles in a sound wave's path expanded and rapidly collapsed¿heating the gas inside them to temperatures hotter than the sun's surface. This collapse and heat, they determined, created a glowing plasma.
In this week's issue of Physical Review Letters, Gary A. Williams and his colleagues from the University of California at Los Angeles present evidence that lends further support to that theory. The researchers set out to explain earlier observations that the spectra of light from a single bubble lacked an emission line¿for the molecule OH¿seen from multiple bubbles.
Because of the discrepancy, some had suggested that different physical mechanisms were at work and that there were, in essence, two kinds of sonoluminescence. But Williams's group proved that isn't the case, creating larger-than-usual single bubbles whose spectra included the missing emission.
Although they don't know why, the researchers say that bubble size alone seems to predict the OH line and suggest that, compared with smaller single bubbles that collapse symmetrically (top right), larger bubbles in multibubble systems are unstable (bottom right). The team further fitted the spectra to a blackbody radiation curve and showed that it corresponded to plasma at a temperature of about 8,000 degrees Kelvin. "It's a nice connecting together of the underlying physical phenomena," Ken Suslick of the University of Illinois in Urbana-Champaign toldPhysical Review Focus. "And the ability to recognize the OH emission line is pretty cool."
When two RIVER meets
There is a special word, which geographers use to designate an area where two or more body waters meet, — confluence.
It can be a place, where a tributary flows into a main river, or a place, where two rivers meet flowing together and creating a new river that has different name.
Here, you will find a number of pictures that show us clearly the boundary between two rivers.
These photos have been collected from all over the world. So, let’s enjoy them!
1. This is a place of confluence of the rivers Rhona and Arve in Geneva, Switzerland. Here is the Rhona in the left part of the picture (the river has its source from Lake Leman). And in the right part there is the Arve flowing from many glaciers in the Chamonix Valley, and then the river flows to the north-west, flowing into the Rhona at the eastern part of Geneva. The Arve has higher level of silt in its water than the Rhona has, and that is why we can see clearly the boundary between them.
2. This is the place, where the rivers Uelzen and Inn meet in Passau, Germany. The Uelzen is rather small torrent carrying blue water, and the Inn is one of the great rivers flowing from Salzburg. The Inn has more powerful stream than the Danube, however, the river flowing out of the city is called the Danube.
3. This is a place of confluence of the rivers Ohio and Mississippi in Cairo, Illinois, the USA. The river Ohio is a tributary of the Mississippi, and flows into it to the south of Cairo, a small town in Illinois. The brown split water of the river Ohio differs greatly from the green and transparent water of the Mississippi (it flows from the north-west to the south). The usual color of the rivers differs from the color of picture, and this is because of strong rain. The waters of the rivers do not mix even 5-6km downstream. (NASA)
4. This is the junction of the rivers Jialing and Chang Jiang in Chongqing, China. The river Jialing is transparent, and its length reaches 119km. It flows into the river Chang Jiang in the city of Chongqing. The transparent Jialing meets the brown Chang Jiang. Taking up the Jialing, the Chang Jiang becomes more powerful and flows through The Three Gorges Dam.
5. Here, we can see a place, where the rivers Rio Negro and Solimoyns meet near Manaus, Brazil. The Rio Negro water has practically black color, and the Solimoyns has sandy-color water. They flows together “side by side” for 6 kilometers. This is one of the most known places of interest in Manaus, Brazil. The waters of the rivers do not practically mix; the reasons of the phenomenon are the difference in temperatures, currents and densities of water of the two rivers. The Rio Negro flows at a speed of 2 kilometers per an hour, and the temperature of its water is 28°C; and at the same time the Solimoyns flows at a speed of 4-6km/h, and its temperature is 22°C. (Immelman284)
6. Here is a place, where the rivers Green and Colorado meet in Canyonlands National Park, Utah, the USA. The river Green is a very long stream in Rocky Mountains. It flows to the south of the Utah, turning to the east and flowing into the Colorado, and then turns to the south again.
7. This is a place of junction of the rivers Thompson and Fraser in Lytton, Britain Columbia, Canada. The river Thompson (transparent) ends in Lytton, Canada, where it flows into the Fraser (turbid). (siacob on Flickr)
9. Here, we can see a place of confluence of the rivers Mosel and Rhine in Koblenz, Germany. Here, in Koblenz the river Mosel flows into the Rhine. The name of the city — Koblenz — means “confluence”. (Photo by PETER JANSEN @ Panoramio.com)
10. Here is the place where the rivers Drava and Danube meet not far from the city of Osijek, Croatia. Osijek is situated on the right bank of the river Drava, 25 kilometers away from the place of junction of the rivers. (WWF: Amazon of Europe)
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