They are the world's most deadly storms (worse than tornadoes), and it's crucial to know your hurricane stuff. Whether you're just discussing them over their namesake cocktails in New Orleans or getting a real hurricane warning come through on your phone, it pays to get your hurricane facts straight. 

By Susan Hall Mahon
October 06, 2016
NASA-JSC/digital version by Science Faction/Getty

During hurricane season, it’s important to be prepared… not just with water and flashlight batteries, but with a real understanding of these annual and often deadly storms. Check (and improve) your hurricane IQ with these 10 essential pieces of cyclone knowledge.

1. Why It’s a Hurricane (Not a Typhoon)

Typhoons and hurricanes are both tropical cyclones with winds of at least 74 miles per hour. The only difference is where they are located. Typhoons form in the northwestern Pacific Ocean, while hurricanes occur in the Atlantic, Caribbean Sea, central and northeast Pacific. (Meanwhile, while both these storms are officially cyclones, the term “cyclone” is used to describe storms in the Bay of Bengal and the Arabia Sea).

2. What Makes Them Spin the Way They Do

The answer is easy: North of the equator, hurricanes spin in a counterclockwise motion. South of the equator, they spin clockwise. 

3. Hurricane Season Is a Real Thing

Atlantic and central Pacific hurricane seasons run from June 1 through November 30 (with the most active time in the Atlantic generally being early-to-mid-September).

4. Storm Naming, Part One: Why

Before the early 1950s, tropical storms were just referred to by the year they occurred in (The 1938 New England Hurricane, for example). But smart people realized that it was easier to keep these storms straight (particularly if a number of big ones occurred in one year) if they each had a name—and the shorter and more distinctive the name, the better. It’s interesting to note that in 1953, the US began using female names only for storms; by 1978, the naming process went coed for Northern Pacific Storms and a year later the Atlantic storms went coed as well. (True or False: Hurricanes with female names have killed more people.)

4. Storm Naming, Part Two: How

While NOAA’s National Hurricane Center keeps track of all storm names for each year, the organization doesn’t control the naming—that’s the job of the World Meteorological Organization. For Atlantic hurricanes, the Center uses six lists of 21 names each that rotate each year… meaning that in 1980 and in 1986 the same 21 names are used. More than 21 storms in a year? They go to the letters of the Greek alphabet, in alpha to omega order. Make sense? If a storm is so deadly or costly that its name is forever tied to a particular event (Katrina, for example), that name is retired. We’ll never hear the name Hurricane Katrina regarding a pending storm again, for example. Ever. Once was enough. (To check out all the retired hurricane names, go here.)

5. The Difference Between a Hurricane Watch and a Hurricane Warning

The difference is 12 hours. A watch is issued when a hurricane or tropical storm is possible within 36 hours. A warning is issued when those same conditions are expected within 24 hours.

6. Categories Are Very Specific, and You Need to Pay Attention

Knowing the category of a hurricane can help you understand how threatening it may be. Categories of hurricane are based on the Saffir-Simpson Hurricane Wind Scale, which describes the impact of the storm. A Category 1 hurricane has winds that range from 74 to 95 mph and can be expected to produce some minor damage to property. At the other, devastating end of the spectrum, a Category 5 hurricane has winds at or greater than 155 mph and can cause catastrophic damage to property, humans, and animals. Learn more about all the categories of hurricanes, right here

7. A Hurricane’s Eyewall Is a Dangerous Thing

A hurricane eyewall is the area that directly surrounds the eye (the calm area at the center of the storm). The eyewall is the location within a hurricane where the most damaging winds and intense rainfall are found.

8. Hurricanes Do Have Stronger “Sides”

In general, the strongest winds in a hurricane are found on what’s called the “right side” of the storm. First, understand that the “right” side is defined based on the general direction that the counterclockwise-rotating storm is moving. If the storm is moving to the west, the right side is to the north. If the storm is moving north, the right is to the east. The right side has higher winds because the motion of the hurricane contributes to its swirling winds. Here’s an example: A hurricane with 90 mph winds while stationary would have winds up to 100 mph on the right side and only 80 mph on the left side if it began moving at 10 mph.

9. Storm Surges Are Bad, and Storm Tides Are Math

A storm surge is the onshore rush of seawater pushed by high winds of an approaching or landfalling tropical storm or hurricane. In other words, the surge is an abnormal rise of water generated by the storm above and beyond the normal astronomical tide. But a storm tide is that number plus the tide’s height. In other words, let’s say the normal high tide is two feet above sea level. Then, a hurricane arrives and causes a storm surge of  +15 feet. The resulting storm tide is +17 feet.

10. Tornadoes Are Horrible, But Hurricanes Are Worse

Even though the winds from the strongest tornadoes are much higher than those of the strongest hurricanes (tornadoes peak in the 207 mph area while hurricanes max out around 131+ mph), hurricanes tend to cause much more destruction than tornadoes because of their size, duration and variety of ways to damage items. The hurricane’s eyewall, for example, can be tens of miles across, last hours and damage structures through storm surge, rainfall-caused flooding, as well as wind impacts. Tornadoes, in contrast, tend to be a mile or smaller in diameter, last for minutes and primarily cause damage from their extreme winds.