Those of you stuck in the arctic wasteland that is the East Coast and parts of the Mid-West right now have probably had a few hypothermia-induced fantasies about how to clear out the snow in front of your car. However, that flamethrower rig you've been concocting won't work. Allow XKCD to explain.
Matt Van Opens wrote into everyone's favorite web-comic:
I've long thought about putting a flamethrower on the front of a car to melt snow and ice before you drive across it. Now I've realized that a flamethrower is impractical, but what about a high-powered microwave emitter?
Putting aside the legal issues and safety hazards of blasting microwaves ahead of you – let alone shooting a wall of fire in your path – there's some hard scientific reasons why both of these ideas wouldn't work.
First off, snow takes a ridiculous amount of energy to melt. XKCD does the math and figures that to clear a 9-foot-wide swath of road covered in one foot of snow at 55 MPH, you'd need 574 megawatts of energy – about three times more than the nuclear reactor fitted to an aircraft carrier.
As for the flamethrower idea, it could work, but you'd need to be plumbed into a gas pipeline – you'd be getting about 17 feet per gallon.
But those are just the basics. Head over to XKCD to get into the nerdy nitty gritty.