Does this video really show oil raining down on Louisiana? Doubtful. What you're likely seeing here, scientists say, is regular water falling onto an oily street and washing that far more common form of pollution down the sewer grate.
But, does that mean oil in ocean water can't possibly become involved in the hydrologic cycle? Nope. There is some evidence, according to the Christian Science Monitor, that floating oil can evaporate under the right conditions. In that case, though, you wouldn't get oil droplets falling from on high. The more likely result would be normal-looking rain tainted with chemical compounds from the oil. According to Popular Mechanics, the only way you'd really get black "rain" is if a hurricane picked up polluted water and dumped it—sans evaporation—onto a coastal area.