The real reason onions make you cry

Even if you love the taste of onions, chances are good that you hate cutting them. The burning sensation, the tears, and if you've ever made the mistake of wiping your eyes with your hand? You're in for a world of hurt. But there's some pretty neat science going on in your kitchen when you're chopping onions, and knowing why you're finding yourself brimming with tears is the first bit of knowledge you need if you want to prevent that flow. And who doesn't want to cry less?