› added 7 years ago

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Pyrocumulus clouds tower tall above a wildfire in these photos taken last week from an Oregon National Guard F-15C.

Most cumulus clouds form when the sun-warmed surface heats air, causing it to rise and carry moisture upward where it condenses to form clouds. In pyrocumulus clouds, the driving heat is supplied by a forest fire or volcanic eruption. The hot, rising air carries smoke and soot particles upward, where they become nucleation sites for condensation. Pyrocumulus clouds can be especially turbulent, and the gusting winds they produce can exacerbate wildfires. In some cases, the clouds can even develop into a pyrocumulonimbus thunderstorm with rain and lightning.

45KN TIL that Microsoft owned www.bob.com, and wanted www.windows2000.com. At the same time, a man named Bob owned www.windows2000.com, and wanted www.bob.com. So they swapped.
W79ed TIL In 1996, Canada became the first country in the world to privatize its air navigation services.
5YLoR TIL In the '80s, the drinking age was raised from 18 to 21 nationally because Reagan passed a bill in 1984 that required states to raise their drinking age to 21. They don't have to make it 21 per se, but if they chose to opt-out, they would simply be ineligible for federal highway funding.
JDm8 TIL that tsunamis can travel unnoticed in deep water as fast as 500 miles an hour, and cross an entire ocean in less than a day.
yQg08 TIL that in 1964, Isaac Asimov speculated that by 2014, cars with "robot-brains" would drive us to our destinations without human assistance. Though he did predict the advent of the autonomous car, his belief that it would hover two feet above the ground failed to materialize.