Yes and no. The funnel of a tornado does not have to reach the ground for damaging winds to occur at ground level. However, if those winds reach the ground then the tornado has touched down even if the funnel hasn't.
It varies widely. The average tornado is on the ground for about 8 kilometers. But some tornadoes are only on the ground for a few meters. At the other end, other tornadoes have had damage paths hundreds of kilometers long. The longest tornado damage path on record is 352 kilometers.
By the meteorological definition a tornado extends from cloud base to the ground. If it does not, it cannot produce damage. However, just because the visible funnel doesn't touch the ground doesn't mean the strong winds don't. It is the vortex of wind which defines a tornado, not the funnel.
A tornado is defined as a violently rotating column of air extending from the base of a thunderstorm to the ground. So in order to be categorized as a tornado, a storm must rotate, connect to both the cloud base and the ground, and have ground level winds strong enough to cause damage.
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By definition a tornado must be in contact with both the ground and the cloud base. So, in that sense, yeas. But this only means that the violent circulation must make this connection, not necessarily the visible funnel. Additionally, sometimes a tornado starts to form, but dissipates before touching down, but in that case it is not considered a tornado.
A tornado. a tornado
a funnel cloud touching the ground is then called a tornado
A tornado often appears dark were it is touching the ground be cause the powerful winds of the tornado lift dirt from the ground.
A funnel cloud that touches the ground is a tornado.
tornado
The intensity of a tornado is rated based on damage done on the ground.
When a tornado touches down it means that it has reached the ground and can now cause damage. Prior to touching down a funnel cloud is usually visible, hanging fro the base of the thunderstorm. It does not qualify as a tornado until damaging winds reach ground level.
A tornado that doesn't touch the ground isn't a tornado; it is a funnel cloud. However if the funnel is pulling debris off the ground or making some other type of contact with the ground it is a tornado.
Yes, it must extend from cloud base to the ground.
When a tornado touches down it means it has reached the ground and can now cause damage. It is not a tornado until this occurs,
A space tornado can cause serious damage, usually 2-4 miles wide if it touches ground. But most of the time, it doesn't touches ground
The Tri-State tornado had the longest damage path. 219 miles