NASA Researchers Reveal Russian Meteorite Explosion in February Generated Dust Plume Over Arctic

NASA does it's usual fantastic job of animated 3D visuals to show how a plume of dust encircled the northern hemisphere above about 50 degrees latitude within days after the February 15, 2013 meteorite explosion over Chelyabinsk, Russia.
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Two plumes were generated - one that covered about 1/2 the Arctic Ocean and a second, larger plume that covered Russia, Canada and northern Europe. The meteor was estimated to weigh about 11,000 tons compared to the average of about 30 tons of space dust that enters earth's atmosphere each day. In other words, about 1 years' worth of normal space debris was vaporized on February 15.  Thinking back on the colder than usual weather conditions in the northern latitudes that continued all the way into June, it seems pretty logical that the meteor dust plumes reducing sunlight penetration to the earth's surface are the reason for the colder conditions and also could explain the recent 50% increase in Arctic sea ice this year compared to 2012. Similar to a small volcanic eruption, we can expect the effects of the meteor dust plume to dissipate quickly.

Shown below are the paths of 1,400 asteroids tracked by NASA that have a chance of hitting earth.

Looks like the electron cloud of an atom doesn't it?  NASA estimates there are about 9,500 potentially hazardous asteroids (PHA) but they have only located about 1/2 of them.