Pressure difference and high-speed winds are causes of __.
Cyclone
Cyclones are caused by high-speed winds and air pressure i.e. atmospheric disturbances around a low-pressure area distinguished by swift and often destructive air circulation. Therefore both high-speed winds and pressure difference are the primary causes of cyclones.
Earthquake and tsunami are caused due to disturbances under the Earth surface.
Hailstorm is the phenomenon in which a heavy rainfall is accompanied by lumps of ice. (hailstone)