Discovery Guides Areas


An Overview and Brief History of Southern Hemisphere Tropical Cyclones
(Released June 2012)

  by Adam Arnold  


Key Citations





Coriolis Effect: A force that causes deflection of moving objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the rotation of Earth.

Hectopascal (hPa): Also known as the millibar (mb), it is the standard meteorological unit of atmospheric pressure.

Intertropical Convergence Zone (ITCZ): The area in the tropics where the trade winds originating from the southern and northern hemispheres are divided. Along portions of the ITCZ, these winds converge, causing air to rise and form large bands of thunderstorms.

Knots (kts): A unit of velocity measured in nautical miles per hour. This unit is the international meteorological standard for reporting wind speeds at sea.

Recurvature: The point at which a tropical cyclone ceases to be equatorwards of a subtropical high pressure system, which causes the tropical cyclone to stop moving westwards, and instead, move towards the poles around the edges of a subtropical high (NW/N/NE in the Northern Hemisphere and SW/S/SE in the Southern Hemisphere).

Storm surge: The coastal flooding that occurs when a tropical cyclone makes landfall. Also known as a storm tide, it is caused by the momentum of the winds of a system pushing large amounts of water across a large area towards a coastline.

Subtropical cyclone: A cyclone that has neither fully tropical/warm core, nor fully mid-latitude/cold core characteristics.

Synoptic: A meteorological scale referring to weather or climate data across a wide area.

Vorticity: A measure of local rotation in a fluid flow.

Warm-core cyclone : A cyclone characterized by higher air temperatures in its center versus its periphery, such. Examples include tropical cyclones and polar lows. This is the opposite of a cold-core cyclone.

Wind shear: A measurement of the difference in direction and velocity of the wind at different vertical levels in the atmosphere.