The Bagnold formula, named after Ralph Alger Bagnold, relates the amount of sand moved by the wind to wind speed by saltation. It states that the mass transport of sand is proportional to the third power of the friction velocity. Under steady conditions, this implies that mass transport is proportional to the third power of the excess of the wind speed at any fixed height over the sand surface over the minimum wind speed that is able to activate and sustain a continuous flow of sand grains.
It has later been modified by several researchers, but is still considered to be the benchmark formula. Iron powder A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material.
In particular, powders refer to those granular materials that have the finer grain sizes, and that therefore have a greater tendency to form clumps when flowing. Granulars refers to the coarser granular materials that do not tend to form clumps except when wet. Types Many manufactured goods come in powder form, such as flour, sugar, ground coffee, powdered milk, copy machine toner, gunpowder, cosmetic powders, and some pharmaceuticals. In nature, dust, fine sand and snow, volcanic ash, and the top layer of the lunar regolith are also examples. Because of their importance to industry, medicine and earth science, powders have been studied in great detail by chemical engineers, mechanical engineers, chemists, physicists Travel in a Dead World first published ; reprinted by Eland in is a travel book, written by Ralph A.
It is still considered a classic work,[3][4] and in , it was reissued by Eland. Travel in a Dead World. Retrieved 12 September Travel in a Dead World".
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Bagnold, Ralph Alger Sharp retired in but continued leading geological field trips afterwards with emphasis on the Grand Canyon geology using rubber rafts. Professor Sharp won t This is a list of important publications in geology, organized by field.
Some reasons why a particular publication might be regarded as important: Topic creator — A publication that created a new topic Breakthrough — A publication that changed scientific knowledge significantly Influence — A publication which has significantly influenced the world or has had a massive impact on the teaching of geology.
Compilations of important publications can be found in Further reading. Foundations Steno, Nicolas Established the following stratigraphical principles: Transactions of the Royal Society of Edinburgh. The index of physics articles is split into multiple pages due to its size. To navigate by individual letter use the table of contents below.
A, B, and C represent the soil profile, a notation firstly coined by Vasily Dokuchaev, the father of pedology; A is the topsoil; B is a regolith; C is a saprolite, a less-weathered regolith; the bottom-most layer represents the bedrock. Surface-water-gley developed in glacial till, Northern Ireland.
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Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil is the pedosphere, which has four important functions: The pedosphere interfaces with the lithosphere, the hydrosphere, the atmosphere, and the biosphere. Soil consists of a solid phase of minerals and organic matter the soil matrix , as well as a porous phase that holds gases the soil atmosphere and Conifers in Germany are damaged by windthrow Wind diagram displaying the mistral wind Wind as portrayed in the Tacuinum Sanitatis Downburst Wind is the flow of gases on a large scale.
On the surface of the Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the Sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect. The strongest observed winds on a planet in the Solar System occur on Neptune and Saturn.
Winds have various aspects, an important one being its velocity wind speed ; another the density of the gas involved; another its energy content or wind energy. Wind is also a great source of transportation for seeds and small birds; with time things can travel thousands of miles in the wind.
The Physics of Blown Sand and Desert Dunes - R. A. Bagnold - Google Книги
Evidence of common descent of living organisms has been discovered by scientists researching in a variety of disciplines over many decades, demonstrating that all life on Earth comes from a single ancestor. This forms an important part of the evidence on which evolutionary theory rests, demonstrates that evolution does occur, and illustrates the processes that created Earth's biodiversity. It supports the modern evolutionary synthesis—the current scientific theory that explains how and why life changes over time. Evolutionary biologists document evidence of common descent, all the way back to the last universal common ancestor, by developing testable predictions, testing hypotheses, and constructing theories that illustrate and describe its causes.
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Comparison of the DNA genetic sequences of organisms has revealed that organisms that are phylogenetically close have a higher degree of DNA sequence similarity than organisms that are phylogenetically distant. Genetic fragments such as pseudogenes, regions of DNA Mars as seen by Rosetta in The climate of the planet Mars has been a topic of scientific curiosity for centuries, in part because it is the only terrestrial planet whose surface can be directly observed in detail from the Earth with help from a telescope.
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It has attracted sustained study from planetologists and climatologists. While Mars's climate has similarities to Earth's, including periodic ice ages, there are also important differences, such as much lower thermal inertia. The climate is of considerable relevance to the question of whether life is or was present on the planet. The climate briefly received more interest in the news due to NASA measurements i A mirror, reflecting a vase A first surface mirror coated with aluminum and enhanced with dielectric coatings. The angle of the incident light represented by both the light in the mirror and the shadow behind it matches the exact angle of reflection the reflected light shining on the table.
Mirror image in a surveillance mirror, which reflects the person taking the photo. A mirror is an object that reflects light in such a way that, for incident light in some range of wavelengths, the reflected light preserves many or most of the detailed physical characteristics of the original light, called specular reflection.
This is different from other light-reflecting objects that do not preserve much of the original wave signal other than color and diffuse reflected light, such as flat-white paint. The most familiar type of mirror is the plane mirror, which has a flat surface. Curved mirrors are also used, to produce magnified or diminished images or focus light or simply distort the reflected image. Destroyed in Seconds was a half-hour American television series that aired on Discovery Channel. Hosted by Ron Pitts, it features video segments of various things being destroyed fairly quickly hence, "in seconds" such as planes crashing, explosions, sinkholes, boats crashing, fires, race car incidents, floods, etc.
The nature of the show closely resembles Real TV. The show uses real video of real events, and commentary explaining the destruction portrayed. Most videos have stock sound effects added. Some of the events seen resulted in fatalities but if so, very few , and all of the events have property damage. Format Usually, if a destruction is horrible, very dangerous, heart-stopping, or results in many injuries, the show usually goes into commercial either right at the moment of impact, right before it, or a little afterwards.
When the show starts again, it reviews what happened and then explains what started the incident. Episodes Season 1 completed on March 23, This is a list of Destroyed i Blue is one of the three primary colours of pigments in painting and traditional colour theory, as well as in the RGB colour model. It lies between violet and green on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately and nanometres. Most blues contain a slight mixture of other colors; azure contains some green, while ultramarine contains some violet.
The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall scattering explains blue eyes. Distant objects appear more blue because of another optical effect called atmospheric perspective. Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments.
In the eighth century Chinese artists used coba The following outline is provided as an overview of and introduction to oceanography: Oceanography — What type of thing is oceanography? Oceanography can be described as all of the following: It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics; plate tectonics and the geology of the sea floor; and fluxes of various chemical substances and physical properties within the ocean and across its boundaries.
These diverse topics reflect multiple disciplines that oceanographers blend to further knowledge of the world ocean and understanding of processes within: The physics of blown sand and desert dunes. Progress in Physical Geography. Physics books Revolvy Brain revolvybrain. Dune topic Erg Chebbi, Morocco In physical geography, a dune is a hill of loose sand built by aeolian processes wind or the flow of water. Member feedback about Dune: Coastal and oceanic landforms Revolvy Brain revolvybrain.
Desert topic Valle de la Luna "Valley of the Moon" in the Atacama Desert of Chile, the world's driest non-polar desert Sand dunes in the Rub' al Khali "Empty quarter" in the United Arab Emirates A desert is a barren area of landscape where little precipitation occurs and consequently living conditions are hostile for plant and animal life. Member feedback about Desert: Ecosystems Revolvy Brain revolvybrain. Member feedback about Ralph Alger Bagnold: Wollaston Medal winners Revolvy Brain revolvybrain.
Granular material topic Examples of granular materials A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact the most common example would be friction when grains collide. Part Two considers small-scale surface phenomena, such as ripples and ridges, and the closely related subject of size-grading the grains. The third part uses the foregoing results to explain the growth and movement of dunes in general, and the peculiar characteristics of the two main dune types.
A method of determining the internal structure of accumulated sand illuminates both the sand's carrying power for motor transport and its water-retention potential. A final chapter, derived from firsthand knowledge, examines the intriguing subject of "singing sand. Paperback , pages. To see what your friends thought of this book, please sign up. Lists with This Book. Jul 13, Ishan rated it it was amazing. This book is a classic.
If you are willing to labor through the scientific details, you'll be entertained by the surprising physics of sand behavior and granular materials. Also, there is a treat for the readers in the last chapter's discussion of 'singing sand'. Sep 15, Ooi Ghee Leng rated it it was amazing. It is astounding when one stops to think of how insightful a pioneering work as that put forth by Bagnold in a concentrated volume seems to not falter in strength, but rather builds up to such a climax in the last chapter of "The Singing Sands".
Also, the passage of time has not buried this work; time has made it into something entirely new, as if the book can metamorphize like natural rock. The physics of granular materials has only started to catch the attentions of physicists in the past deca It is astounding when one stops to think of how insightful a pioneering work as that put forth by Bagnold in a concentrated volume seems to not falter in strength, but rather builds up to such a climax in the last chapter of "The Singing Sands".
The physics of granular materials has only started to catch the attentions of physicists in the past decade after centuries of ignorance, albeit its apparent importance in a lot of industries.
The Physics of Blown Sand and Desert Dunes
Bagnold only probes the physics of blown sand and desert dunes, but in that process, he opens up a horizon of potential projections of the reported observed phenomena in other fields like geomorphology, landslide physics, and etc. This is how a scholarly book should be written. Mathematical and yet lucid as insights are the founding structures from one explained equation and phenomenon to the other. Bagnold set an excellent academic example which we scientists, who are still striving hard to decipher the science behind granular materials, shall adhere to. May 19, Bill rated it really liked it.
A beautiful example of science writing. Although it is loaded with physics and equations that I barely understand I thoroughly enjoyed his clear descriptions of the questions he set out to answer and the methods he used to find these answers. This is the foundational work of the study of the movement by wind of sand and is still used today in college level courses. Jun 14, William Herschel marked it as interesting-nonfiction. Rick Steffers rated it it was amazing Mar 06, Jeremiah Collatz rated it it was amazing Feb 17, Alex Rinehart rated it it was amazing Sep 06, Abdallah Samy rated it did not like it Apr 17, Thomas Lanagan rated it really liked it Jul 30, Stephen rated it it was amazing Nov 27, Daniel rated it really liked it Apr 01, Dave rated it liked it Jan 01, El rated it really liked it Nov 02, Emily Kellagher rated it really liked it Apr 20, Anna marked it as to-read Aug 07, Alex is currently reading it Jul 27, Laura marked it as to-read Nov 14, Shahab marked it as to-read Dec 26,