A tornado is a rotating column of air extending from a thunderstorm to the ground.
"A tornado is several severe thunderstorms," Meteorologist at the University of Newcastle, Martin Babakhan says.
"A tornado forms with the rotation of these thunderstorms. The rotations develop a tornado within the strong updraft rising air within the storm. This makes the cloud look even darker when you see it from a distance."
Oklahoma's latest deadly tornado roughly followed the same path of another tornado in 1999 which damaged or destroyed more than 8,000 homes, and killed at least two people, experts say.
The United States' National Weather Service estimates this latest storm carried wind speeds of up to 320 km/h and was at least 800 metres wide.
Mr Babakhan says some places are more prone to tornadoes than others.
"Geographically, Oklahoma is located in an area where sea surface temperatures are warm at that time of year, there's a lot of moisture in the upper atmosphere," he says.
The US ranking system for tornadoes ranges from EF0 (for the least severe tornadoes) to EF5.
The most recent tornado in Moore has been ranked as an EF4, carrying winds between 267 and 322 km per hour.
Mr Babakhan says such intensity is rare, but that it is likely to become more common in the future.
"This has become a very, very strong category thunderstorm," he says.
"All the studies show now that yes, the climate has warmed up. When you get a warming climate, the moisture level increases in the upper atmosphere, so the atmosphere becomes very dynamically suitable for these kinds of weather conditions."
