Hurricane Irene is barreling towards the Eastern seaboard, with serious disaster preparations underway in many cities and towns. In New York City they're taking the danger from Irene so seriously that they're shutting down the entire subway system, as well as all buses and commuter trains, starting with the final run of all vehicles at midday Saturday.
This is shaping up to be a potentially huge storm - and hurricanes are no laughing matter. Hurricane Katrina caused an estimated 1,836 deaths, and approximately $81 billion in damage, back in 2005.
Hurricanes occur an average of 10-15 times per year around the world. Tornadoes, on the other hand, are much more common, with around 1200 twisters touching down in the United States alone every year.
For more on the difference between hurricanes and tornadoes, check out this handy infographic (click for full-size version):