Whiteout (weather) moving. Local, short-duration whiteout conditions can be created artificially in the vicinity of airports and helipads due to aircraft operations. Snow on the ground can be stirred up by helicopter rotor down-wash or airplane jet blast, presenting hazards to both aircraft and bystanders on the ground. Whiteout (weather) Whiteout is a weather condition in which visibility and contrast are severely reduced by snow or sand. The horizon disappears from view while the sky and landscape appear featureless, leaving no points of visual reference by which to navigate. Whiteout has been defined as: "A condition of diffuse light when no shadows
Quadratic irrational number be proved irrational. Theodorus of Cyrene proved the irrationality of the square roots of whole numbers up to 17 (except those few that are square numbers, such as 16), but stopped there, probably because the algebra he used could not be applied to the square root of numbers greater than 17. Euclid's Elements Book 10 is dedicated to classification of irrational magnitudes. The original proof of the irrationality of the non-square natural numbers depends on Euclid's lemma. Many proofs of the irrationality of the square roots of non-square natural numbers implicitly assume the fundamental theorem of arithmetic, which was first