Forme des cristaux de neige et origine des avalanches. Forme des cristaux de neige et origine des avalanches Étienne REYSSATClaire TAMAIN Introduction : Les premières études des cristaux de neige se bornaient à décrire les différentes formes qu'ils pouvaient prendre.
Aujourd'hui, on en fait une approche plus scientifique, avec des moyens plus évolués, dans le but de comprendre leur formation et leur évolution. De plus, l'étude des cristaux n'est plus une fin en soi, mais elle a notamment pour objectif d'expliquer comment les transformations des cristaux peut aboutir au phénomène d'avalanche. I. Johannes Kepler : En 1611, Kepler publie un petit traité qui est une des premières approches scientifiques de l'étude des cristaux de neige. René Descartes : Descartes est le premier, en 1635, à décrire précisément plusieurs formes de cristaux de neige. Robert Hooke : En 1665, l'invention récente du microscope permet à Hooke de réaliser des observations encore plus précises. Wilson A. Bentley était un fermier et un photographe Américain. Ukichiro Nakaya b. Wellcome Image Awards 2012.
Flowering plant. The ancestors of flowering plants diverged from gymnosperms around 245–202 million years ago, and the first flowering plants known to exist are from 160 million years ago.
They diversified enormously during the Lower Cretaceous and became widespread around 120 million years ago, but replaced conifers as the dominant trees only around 60–100 million years ago. Angiosperm derived characteristics[edit] Flowers The flowers, which are the reproductive organs of flowering plants, are the most remarkable feature distinguishing them from the other seed plants. Flowers aid angiosperms by enabling a wider range of adaptability and broadening the ecological niches open to them. [clarification needed] This has allowed flowering plants to largely dominate terrestrial ecosystems.
These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants and the most commercially important group to humans. Evolution[edit] Classification[edit] Why do whispering women cause ASMR brain orgasms? Dimensional-Images.jpg (1920×1200) Minerals - Maggie's Science Connection. How a Photographer Created Images of Fireworks Unlike Any You've Ever Seen - Megan Garber. A photographer's experiment puts explosions in new light.
A spaceship? A sea creature? A spunky chapeau? Nope: fireworks. (David Johnson) Earlier this month, David Johnson found himself at the International Fireworks Show in Ottawa, Canada. The resulting images, which I first saw on the blog This Is Colossal, are mesmerizing. As Johnson later told me of his method: The way I captured the photos was actually pretty simple... it just required good timing. It does! A dandelion: A group of dandelions: A sunflower: Thistles: Spores: Viruses: An armored insect: You can see more over at Johnson's website, here.
Via Steve Silberman and This Is Colossal. A small (but glorious) world: The best microscope images of 2012. Most people know Nikon as a purveyor of pro and consumer-grade digital cameras.
But the company's expertise with optics bleeds over into related markets—it's one of the science community's major suppliers of microscopes. And each year the company asks the community to send it some of their favorite images of tiny objects. A panel of scientists and journalists have chosen the best of this past year's submissions, which Nikon has placed on its Small World site. We've gone through and picked out some of our favorite images from this year, and Nikon provided some high-resolution versions. In keeping with the Ars tradition, where possible, we'll tell you a bit more about the subjects than you might get from the brief description on the original site. The grand prize winner at top highlights the blood vessels as they form in the brain of a zebrafish.
Confocals only capture light from a single plane of focus, so each individual image is like an optical slice through the tissue.