Whiteout (weather)

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Whiteout is a weather condition where heavy snow, fog, or blowing sand makes it very hard to see and to judge distances. The horizon disappears and the sky and ground look alike, giving almost no visual references for navigation. A true whiteout can happen with very heavy snowfall (for example lake-effect snow) or when diffuse light from clouds, mist, or a snowy background scatters sunlight. People moving in a whiteout can become disoriented and lose their way, even in familiar surroundings. Drivers may have to stop because the road is invisible.

Normal snowfalls or blizzards with moderate snow and partial visibility are often not true whiteouts.

There are different forms of whiteout, and it should not be confused with flat-light, which is just diffusion of light rather than a reduction of contrast.

Whiteout conditions threaten climbers, skiers, pilots, and motorists, especially on high-speed roads. Major multi-vehicle crashes have occurred in whiteouts. In some cases, artificial whiteouts can occur near airports or helipads due to aircraft operations, as rotor wash or jet blasts stir up snow and create hazards for aircraft and people on the ground.