Not necessarily. Although tropical cyclones can only form over warm ocean water, extratropical cyclones can form over land.
In the US, a cyclone can only start over land - over the water it is referred to as a water spout.
Cyclone Tracy started as a tropical storm out in the Arafura Sea.
wc
A cyclone occurs over water. A hurricane occurs over land.
cyclone yasi travled about 500m a hour to start of with but then it got slower, the cyclone was sopost to hit at 9pm but it slowed down so it hit at about mid night
As a cyclone moves over land, it loses its main energy source of warm ocean water, causing it to weaken. The friction from the land also disrupts the structure of the cyclone, causing it to break apart and dissipate more quickly than if it were over water.
Tornado Cyclone Hurricane (with water)
It isn't.
As is the case with all tropical cyclones, Cyclone Yasi was generated from a low pressure system out at sea some days earlier.
The Gladstone cyclone in 1949 was known as Cyclone Mahina. It struck the town of Gladstone in Queensland, Australia on March 10, 1949. Cyclone Mahina caused significant damage and loss of life in the region.
Because of air pressure
This link has all the info you need.