Define Cyclone 

low pressure surrounded by a high pressure

when wind from one side and wind from another side clash with each other they form a cyclone

a system of winds rotating inwards to an area of low barometric pressure, with an anticlockwise (northern hemisphere) or clockwise (southern hemisphere) circulation; a depression

It is a large scale air mass that rotates around a strong centre of low atmospheric pressure

spiralling winds formed in a tropical seas due to formation of low pressure region in sea and moving at speed of 120 km / hr is called a cyclone .

 an extremely large, powerful, and destructive storm with very high winds that turn around an area of low pressure....

water absorbs heat from the atmosphere to change it into vapour state . when water vapour converts back into liquid state as raindrops this heat is released in the surrounding air . this warm air tends to rise up causing a decrease in air pressure . more air rushes towards the centre of the strom. this cycle is repeated . a very low pressure system with very high speed wind revolving around it is formed . this is called cyclone .