There is no "why" it is natural.
Tornado Glory was created in 2004.
Tennessee Tornado was created in 1999.
Dallas Tornado was created in 1967.
Red Tornado was created in 1968.
The Human Tornado was created in 1976.
House Tornado was created in 1988.
Tornado Rex was created in 1991.
Laredo Tornado was created in 1973.
Tornado Luxembourg was created in 1987.
Blue Tornado was created in 1998.
Blackhawk - Tornado - was created in 1979.
Panavia Tornado was created in 1979.