Livres sur le sujet « NATURAL SUNLIGHT »

This article examines Isaac Newton’s contributions to the development of optics. Newton’s Opticks: Or, a Treatise of the Reflexions, Refractions, Inflexions and Colours of Light (1704) dominated the science of optics for more than a century. His theory of colour and the compound nature of sunlight was central to modern optics. This article first considers Newton’s reflecting telescope before discussing the fundamental elements of his theory of the nature of white light and colour. It then evaluates the reception toward Newton’s ‘new theory about light and colour’ and his refinement of the theory, along with his corpuscular optics, with emphasis on his explanation regarding refraction and dispersion. It also explores Newton’s ideas about the colours of natural bodies and of thick plates, his theory of fits, and the delayed publication of the Opticks. Finally, it reflects on Robert Hooke’s influence on Newton’s concept of diffraction.

Get ready for lift-off on a Martian adventure! Have you ever imagined living on another planet? What about Mars? With not enough air to breathe, sunlight to keep us warm, or any available food and water, life on Mars is going to be a challenge... but it just might be possible! Take a journey to the Red Planet in How to Survive on Mars. Discover natural wonders like ancient polar ice caps, the highest volcano in the solar system and a 45-kilometre-wide impact crater that was once a Martian lake. Packed with stunning photographs, fun activities and quizzes, this book will show you what you need to do to survive on Mars! Join scientists, engineers, archaeologists, ethicists and science-fiction writers for a space exploration adventure. Reading level varies from child to child, but we recommend this book for ages 8 to 12.

Situated at the southern edge of the Tibetan Plateau (TP), the Hindu-Kush-Himalayas-Gangetic (HKHG) region is under the clear and present danger of climate change. Flash-flood, landslide, and debris flow caused by extreme precipitation, as well as rapidly melting glaciers, threaten the water resources and livelihood of more than 1.2 billion people living in the region. Rapid industrialization and increased populations in recent decades have resulted in severe atmospheric and environmental pollution in the region. Because of its unique topography and dense population, the HKHG is not only a major source of pollution aerosol emissions, but also a major receptor of large quantities of natural dust aerosols transported from the deserts of West Asia and the Middle East during the premonsoon and early monsoon season (April–June). The dust aerosols, combined with local emissions of light-absorbing aerosols, that is, black carbon (BC), organic carbon (OC), and mineral dust, can (a) provide additional powerful heating to the atmosphere and (b) allow more sunlight to penetrate the snow layer by darkening the snow surface. Both effects will lead to accelerated melting of snowpack and glaciers in the HKHG region, amplifying the greenhouse warming effect. In addition, these light-absorbing aerosols can interact with monsoon winds and precipitation, affecting extreme precipitation events in the HKHG, as well as weather variability and climate change over the TP and the greater Asian monsoon region.

Naturopathic medicine is a stand-alone system of whole-person health care rooted in traditional European nature cures of diet, rest, sunlight, fresh air, exercise, and water. Modern naturopathic physicians are trained as primary care licensable physicians whose education is recognized by the Department of Education. Medically trained naturopathic doctors (NDs) are ideal providers to thoroughly care for the geriatric patient. NDs are trained in conventional assessment and treatment but also in evaluation of underlying functional etiologies and holistic treatments such as diet, lifestyle, physical medicine, and herbal and homeopathic interventions. These provide comprehensive and extensive health care options that move away from the polypharmacy options so prevalent in this population. Medically trained naturopathic physicians are beneficial members of any geriatric medical team.

Over time, the Earth’s habitability for human beings has changed tremendously, despite the mild, slow changes in the Sun’s intensity and the slight shifts in Earth’s orbit: cycles of “Snowball Earth” put mile-deep glaciers all over the Earth, even into the tropics, whereas longer ago the atmosphere was completely different and impossible for humans to survive in. The interdisciplinary science of planetary habitability is revealing the intrinsic duality of processes that are both beneficial and detrimental to life: sunlight, magnetism, volcanism, chemical weathering, asteroid impacts, and even life around us. With so many processes, the balancing act of our comfortable planet is remarkable, perhaps unique. Ultimately, nature will destroy our habitable home, but not likely for a very, very long time, provided we ourselves do not cause things to derail.

The Arctic part of the North American continent has seen some of the most fascinating and demanding human adaptations anywhere, culminating in those of the Inuit who live there today. This region is characterized by persistence of cold (long winters and short cool summers), permafrost (year-round frozen ground), large seasonal differences in the amount of sunlight, few or no trees, and a minimum of plant foods directly consumable by humans. To survive in this environment the Inuit peoples and their predecessors, of necessity, relied on technology and on animal resources to a greater extent than recent hunter-gatherer populations anywhere else in the world. This chapter explores the ethnographic and archaeological records of these peoples and this region to study the nature of childhood in prehistoric hunter-gatherer populations.

Most scientists now agree that some sixty-five million years ago, an immense comet slammed into the Yucatan, detonating a blast twenty million times more powerful than the largest hydrogen bomb, punching a hole ten miles deep in the earth. Trillions of tons of rock were vaporized and launched into the atmosphere. For a thousand miles in all directions, vegetation burst into flames. There were tremendous blast waves, searing winds, showers of molten matter from the sky, earthquakes, and a terrible darkness that cut out sunlight for a year, enveloping the planet in freezing cold. Thousands of species of plants and animals were obliterated, including the dinosaurs, some of which may have become extinct in a matter of hours. In Impact, Gerrit L. Verschuur offers an eye-opening look at such catastrophic collisions with our planet. Perhaps more important, he paints an unsettling portrait of the possibility of new collisions with earth, exploring potential threats to our planet and describing what scientists are doing right now to prepare for this awful possibility. Every day something from space hits our planet, Verschuur reveals. In fact, about 10,000 tons of space debris fall to earth every year, mostly in meteoric form. The author recounts spectacular recent sightings, such as over Allende, Mexico, in 1969, when a fireball showered the region with four tons of fragments, and the twenty-six pound meteor that went through the trunk of a red Chevy Malibu in Peekskill, New York, in 1992 (the meteor was subsequently sold for $69,000 and the car itself fetched $10,000). But meteors are not the greatest threat to life on earth, the author points out. The major threats are asteroids and comets. The reader discovers that astronomers have located some 350 NEAs ("Near Earth Asteroids"), objects whose orbits cross the orbit of the earth, the largest of which are 1627 Ivar (6 kilometers wide) and 1580 Betula (8 kilometers). Indeed, we learn that in 1989, a bus-sized asteroid called Asclepius missed our planet by 650,000 kilometers (a mere six hours), and that in 1994 a sixty-foot object passed within 180,000 kilometers, half the distance to the moon. Comets, of course, are even more deadly. Verschuur provides a gripping description of the small comet that exploded in the atmosphere above the Tunguska River valley in Siberia, in 1908, in a blinding flash visible for several thousand miles (every tree within sixty miles of ground zero was flattened). He discusses Comet Swift-Tuttle--"the most dangerous object in the solar system"--a comet far larger than the one that killed off the dinosaurs, due to pass through earth's orbit in the year 2126. And he recounts the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994, as some twenty cometary fragments struck the giant planet over the course of several days, casting titanic plumes out into space (when Fragment G hit, it outshone the planet on the infrared band, and left a dark area at the impact site larger than the Great Red Spot). In addition, the author describes the efforts of Spacewatch and other groups to locate NEAs, and evaluates the idea that comet and asteroid impacts have been an underrated factor in the evolution of life on earth. Astronomer Herbert Howe observed in 1897: "While there are not definite data to reason from, it is believed that an encounter with the nucleus of one of the largest comets is not to be desired." As Verschuur shows in Impact, we now have substantial data with which to support Howe's tongue-in-cheek remark. Whether discussing monumental tsunamis or the innumerable comets in the Solar System, this book will enthrall anyone curious about outer space, remarkable natural phenomenon, or the future of the planet earth.