Now I think I heard someone saying that a tornado will spin anti-clockwise in both hemispheres. But I still think that it spins in different directions depending on the hemisphere. If what I think is true, then what would happen if a tornado was to pass right over the equator?
Chosen Answer:
The Coriolis effect is caused by the rotation of the planet about its axis and produces a rotation of one revolution per day as that is the number of revolutions the planet makes in a day. It is proportional to the sine of the latitude so Coriolis is zero at the equator and at a maximum at the poles,
With small scale rotations such as water going down plugholes or dust devils, factors other than Coriolis determine the direction of rotation. Coriolis does affect mesoscale systems like sea breezes and large thunderstorms so the rotation in a thunderstaorm can be determined by Coriolis. If the rotation is determined by Coriolis then any tornadoes produced by the storm will have the same rotation.
This is fine except at the equator where Coriolis is zero. This means that any rotation in the thunderstorm is determined by factors other than Coriolis and any tornadoes could rotate in either direction. If they cross the equator, Coriolis remains zero so there will be no change in rotation.
Hurricanes/Typhoons/Tropical Cyclones (same thing in different locations) cannot form within 5° of the equator as Coriolis is not strong enough to get them revolving. Usually they form 10° or more from the equator. Once they form, the winds are such that they move further from the equator and never cross it.
by: tentofield
on: 13th March 13
