A New Twist on Hurricanes?
Current position of Potential Tropical Cyclone #10. Expected to slide south of Sable Island Wednesday night!
Published Tuesday, August 29, 2017 11:25AM ADT
Last Updated Tuesday, August 29, 2017 11:45AM ADT
While I was sleeping, two interesting questions popped up on my Facebook page; both asking about the term “cyclone”. Sylvia Bourn and Brenda Toope were wondering why and when forecasters started calling hurricanes "cyclones"?
The term is not new. It’s been around forever and describes the direction of rotation around a centre. Winds rotate counterclockwise around a cyclone and clockwise around an anticyclone.
All weather systems in the world are derived from either a cyclone or an anticyclone. This might help: a cyclone is a low pressure system; an anticyclone is a high pressure system. A low pressure system over the prairies is a cyclone too! When cyclones form over the tropics they are referred to as tropical cyclones.
Tropical cyclones are classified into different categories depending on their strength and location. The National Hurricane Center rates them with the use of the Saffir-Simpson Hurricane Scale.
A tropical depression is an organized group of clouds and thunderstorms with a clear surface circulation and maximumsustained winds of less than 62 km/h. It has no eye and does not usually have the spiral shape of more powerful storms
A tropical storm is an organized system with a very clear surface circulation and maximum sustained winds between 63 and 117 km/h. At this point, the cyclonic shape starts to form, although an eye does not usually appear in tropical storms. Storms that reach tropical storm status are given a name.
A hurricane is a cyclonic weather system with sustained winds of at least 118 km/h. A tropical cyclone of this strength usually develops an eye – that area of calm conditions at the center of circulation. The eye is often seen from space as a small, round, cloud-free spot. Surrounding the eye is the eyewall, an area in which the strongest thunderstorms and winds spin around the storm's center.
I hope this little “cyclone” refresher helps clear the air!