Can it really rain frogs?

­­­­It's hard to get a good mental picture of frog­ inundation that doesn't have Moses standing off in the distance. The biblical image of a slimy, surprising mass is tough to avoid. However, there's act­ually a pretty simple explanation for the whole thing: It involves whirlwinds and low-weight creatures­.

­­­­Frogs can weigh as little as a few ounces. But even the heavier ones are no match for a watery tornado, or a waterspout, as it's called when a whirlwind picks up water. The series of events that can lead to frog rain go something like this:

­­­A small tornado forms over a body of water. This type of tornado is called a waterspout, and it's usually sparked by the high-pressure system preceding a severe thunderstorm.­

As with a land-based tornado, the center of the waterspout is a low-pressure tunnel within a high-pressure cone. This is why it picks up the relatively low-weight items in its path -- cows,­ trailer homes and cars get sucked up into the vacuum of the vortex. But since a waterspout is over water and not land, it's not automobiles that end up caught in its swirling winds: it's water and sea creatures. ­

The waterspout sucks up the lower-weight items in the body of water as it m­oves across it. Frogs are fairly lightweight. They end up in the vortex, which continues to move across the water with the high-pressure storm clouds. When a particularly powerful storm hits land, the waterspout might go with it.

When the storm hits land, it loses some of its energy and slows down. The pressure drops. Eventually, the clouds release the water they're carrying. As the rain falls, the vortex eventually loses all the pressure that's keeping it going, and it releases whatever it has picked up in its travels. Sometimes, this cargo includes frogs.

­The end result is frog rain. Sometimes it's a few dozen frogs -- or a couple hundred or even thousands. And usually, it's not just frogs. Frogs get top billing because of their role in Exodus, but waterspouts can carry all sorts of items. So what's the strangest thing that can fall from the sky? Find out next.

Frogs can travel tremendous distances in the vortex of a waterspout. Waterspouts can move across hundreds or thousands of miles, although that's extremely rare. It's more common for frogs to travel just a few miles before they fall to the ground.

Reports of strange objects falling from the sky are numerous and varied. People have reported raining squid, worms and fish. Fish are actually the most common creatures to fall from the sky, for obvious reasons -- they're very lightweight, and they're the most common water inhabitants [source: BBC]. But waterspouts can pick up heavier objects, too.

Waterspout winds can spin at amazing speeds -- up to 200 mph [source: CMMAP]. These types of wind speeds can pick up a very wide range of cargo because they can suck up objects from up to 3 feet (1 meter) below the surface, and the low-pressure core they form is an extremely powerful vacuum compared with the speeding winds surrounding it. Large water birds have also fallen from the sky. At least one source reports a sailboat coming down with rain [source: CMMAP]. Presumably a waterspout can pick up a few things when it hits land, too, because it has also been known to rain tomatoes and coal [source: CMMAP].

But it's when the frogs, fish and other water animals hit the ground that things really get gross. It's unlikely they survive the journey, what with the speeding low-pressure vortex and the impact once that vortex dissolves. Usually, the frogs die, although it's unclear when exactly that happens -- during the trip or as a result of the fall.

However, sometimes the frogs luck out. When it rained frogs in a small town in Serbia in 2005, people walked outside after the storm to see their streets blanketed in frogs trying to hop their way back to water.

For more information on frog rain and related topics, look over the links on the next page.