Dr. Kim Wood

They spin up off of the...

instability that happens between the moist tropical latitudes over equatorial Africa versus the hot, dry Saharan desert.

But the energy that feeds them when they're over Africa, well, it's a little different once they're over the ocean.

You know, if they can start feeding off the energy of the ocean and instability in the atmosphere over the ocean, then they can start to consolidate around a center and spin up into a cyclone.

So they're called cyclones because they're spinning around a particular point.

At that stage, they've gone from a disturbance that we're keeping an eye on to a tropical depression.

So once they get that tropical depression label, they are considered tropical cyclones.

On the Saffir-Simpson hurricane wind scale, we don't use that scale until they've hit 74 miles an hour, which is a category one.

So a tropical storm is 39 to 73 miles an hour, which sounds kind of arbitrary, but that's the range that we use.

So that means a 70 mile an hour tropical storm is only slightly

weaker, so to speak, than a 75 mile an hour hurricane.

But we start paying attention when it flips that category from a tropical storm to a hurricane.

And we also pay attention when it goes from category two to category three, they're major hurricanes.

And then, of course, there's the elusive category five, which there's not much difference between a category four and five.

If you actually go to the Saffir-Simpson hurricane scale description, hurricane wind scale, it is...

Just labeled as catastrophic damage.

So, you know, category five grabs attention, but it's not so much more damaging than a category four.

Category four is pretty bad, too.

Originally speaking, we associated the maximum wind speed with the damage.

Because we wanted people to be prepared for if you got hit with that maximum wind speed, but a hurricane has multiple hazards.