Why do sometimes hurricanes form and sometimes tornados?
2. What time of the year do most tornadoes occur in the USA? 3. Why doesn’t Australia have the severe tornadoes or twisters that occur in the mid west of North America? 4. Do scientists know what factors determine the strength of a tornado? 1. Why do sometimes hurricanes form and sometimes tornados? Hurricanes – what we call tropical cyclones in Australia – form over warm water as air converges into a limited area. As the air moves inward it starts to rise in the centre – after all its got to go somewhere – can’t just keep squashing in, in the middle. Also as it moves in, and up, it starts to turn, because of something called Coriolis force. So you end up with a big mass of rotating air, rising in the centre, a bit like water flowing out of a bathtub, but going up instead of down. As the air rises, it releases the water its accumulated over the warm ocean waters. That makes it warmer, and it rises faster, so more air can come in at the bottom. That air rises, and so on, with the whole
