To be put briefly: rolling air called wind shear gets turned vertical by a thunderstorm's updraft. This starts the storm rotating, turning into a supercell. Under the right conditions this rotating updraft, called a mesocyclone, can tighten and intensify into a tornado.
Tornadoes can happen in any place that gets thunderstorms.
Tornadoes happen in Miami for the same reason they happen anywhere else. See the related question for how tornadoes form in general.
Tornadoes are weather related, and are thus created by nature.
They cannot be controlled. Tornadoes are a force of nature.
Tornadoes can happen in Ottawa. Canada does get tornadoes, though not as often as the U.S. due to its cooler climate.
Tornadoes can happen anywhere in the world except cold areas like Antarctica and the north pole. Tornadoes are mostly common in United States.
Yes. Tornadoes, including some significant ones, can and do happen the the Philippines.
Tornadoes happen in the summer every year.
Most tornadoes in the U.S. happen in spring and early summer.
Tornadoes can happen anywhere - they're usually formed from severe thunderstorms.
Nature has always influenced culture. Nature controls mankind but humans also use nature to their advantages like in agriculture. For Tornadoes, there are some benefits for them. Tornadoes can clear out bad vegetation and to promote growth and I'm sorry to say but can be seen as population control. But maybe that's besides the point. Tornadoes happen because they are one small part of a larger system that helps balance out the earth. Tornadoes may be bad but it's one small sacrifice to promote the other benefits of nature.
Yes. Tornadoes are a type of natural phenomenon.