Tornadoes
Have you ever heard of the saying, it’s raining cats and dogs? Well, in some parts of the world it actually rains frogs, fish or even snails.
Strange as this may sound, these sort of rainstorms have been recorded throughout history. Pliny, a Roman historian, reported a shower of frogs in 77 AD. Another early record of an event of this nature is found in a publication known as the Banquet of the Learned written around 200 AD by the ancient Greek, Athenaeus. At one point in time the sky over Macedonia was dark with frogs, and when they rained down, there were so many it was impossible to walk down the streets without stepping on them. In 1939, a similar frog storm happened in England. More recently, the town of Great Yarmouth on the East Coast of England had small silver fish accompanying the heavy rain of a thunderstorm, much to the amazement of the local residents.
Whirlwinds, waterspouts and tornadoes can all pick up water and any small unsuspecting creatures that happen to be near the surface. They are then carried upwards spun around and later deposited some distance away from where they were picked up. Tornadoes have been known to pick up much larger cargo then mere fish. Whole vehicles have been sucked more than a hundred metres into the air. The energy to do this comes from high windspeed in the funnel, which can be higher than 450 km/h!
If you’ve been to the sea, you will probably be aware of cooling onshore winds that blow in the late afternoon. This happens because as the Sun has shone during the day the land has heated up more than the ocean. The hot land heats the air above it and the hot air rises. The cooler air from above the sea rushes in to take its place, filling the partial void. All winds start like this, as air moves from a higher pressure area to a lower pressure area.
Under certain conditions, the air rush can be great, and with warmer air rising, it can be almost like wind going ‘up the plughole’ and swirling into a spiral as it goes. The upward moving air can drag water and objects up with it. If a tornado forms over the sea it can suck up large amounts of water to form a waterspout reaching into the clouds above. The snake-like appearance of these spouts as they travel made a frightening sight, and they were reported by ancient mariners as sea monsters.
You can come and watch an indoor tornado form before your very eyes at Questacon’s Awesome Earth exhibition. The exhibition allows visitors to discover the power and the beauty of many of the Earth’s natural phenomena and contains 30 interactive exhibits, including a Tornado. Awesome Earth is on permanent display at Questacon.
You can find out more at:
http://www.noaa.gov/tornadoes.html
http://www.nssl.noaa.gov/noaastory/
http://www.bom.gov.au/lam/climate/levelthree/c20thc/storm1.htm
By Ruth Beran
Shell Questacon Science Circus 2003