SCIENCE

Villagers in west Sri Lanka have said they have been surprised and delighted by an unusual rainfall of (edible) small fish. (BBC)

When animals get swept up in clouds, look out below!

Discussion Ideas

• Read our media spotlight “Strange Rains,” which nicely explains how so-called “animal rain” might happen. The spotlight describes two types of weather conditions leading to animal rain: waterspouts and updrafts. Which type of weather probably led to the fishy rain in Sri Lanka?
  • Waterspouts, the most common weather phenomenon associated with animal rain, probably caused the fishy storm in Sri Lanka. According to the BBC analysis, “In the Sri Lankan storm, a tornado probably formed over land, drifted over river systems or coastal waters and sucked up light fish that were lifted all the way into the base of the storm cloud. Later the fish were rained out of the cloud.”

• Read through the “Fast Facts” in our “Strange Rains” media spotlight, which lists examples of animal rain. Find these regions using our MapMaker Interactive, using the “Climate Zones” and “Precipitation/Rainfall” layers. (Adjust the transparency to compare the two physical systems.) What do the “animal rain” regions have in common? Where else might you expect to find outbreaks of animal rain?
  • Animal rain is the result of drastic changes in temperature, humidity, and wind speed. The regions that have experienced animal rain—the southeastern U.S., southern India and Sri Lanka, Japan, the Australian island of Tasmania—all experience moderate-to-heavy precipitation and a humid temperate or equatorial climate. They are also coastal regions where lakes and rivers are common. The climate, rainfall patterns, and proximity to water create the perfect conditions for animal rain.
  • Other regions that might experience animal rain share similar climate, precipitation, and proximity to water. The BBC article mentions “prawn rain” that fell on another part of Sri Lanka recently. The Roman historian Pliny the Elder wrote about a rain of frogs in what is now Italy. Wales, Singapore, Philippines, and Honduras have all experienced fishy rain. (So has the U.S. state of Rhode Island!) It has rained spiders in Brazil. In my favorite story, a North Korean fisherman was knocked out when a frozen squid fell from the sky and hit him on the head during a storm around the Falkland Islands. (If true, the squid was probably swept up by a waterspout to an icy stormcloud, where it then froze. Cephalopod hailstone!)

• So, it’s raining fish . . and bats and birds, spiders and squid, frogs and jellies. Can we expect it to actually rain cats and dogs? (Or ruby-slippered girls, or whales and petunias?)
  • Probably not. Tornadoes and other strong winds are certainly capable of sweeping up objects as big as houses. Tornadoes are swirling winds, however, not quite rainclouds. Cats, dogs, and people are usually too massive to be suspended in a cloud for even a short amount of time.
  • Having said that, scientists are not quite sure how animal rain works. The waterspout theory is just a leading hypothesis and has not been tested or even scientifically observed. It could be the infinite improbability drive after all.