Hurricanes -- like the storm currently making landfall in Florida -- are one of several types of tropical cyclones that occur in oceans and coastal regions.
Tropical cyclones carry heavy rains with them, among other dangerous hazards -- a quality that tends to get their image lumped together with that of other rain-heavy storms and weather patterns, like tsunamis and monsoons. The types of tropical cyclones are similar in nature, but they differ from other wet weather events impacting different regions on Earth.
Below, we’ll take a look at hurricanes, tropical storms, typhoons, monsoons and tsunamis and what makes them different from one another.
Tropical cyclones: Hurricanes, typhoons
Both hurricanes and typhoons fall under the category of “tropical cyclones.” In fact, hurricanes and typhoons are the exact same thing, they’re just called one name or the other depending on where they occur.
A tropical cyclone is a “rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation,” according to the National Ocean Service. There are four types of tropical cyclones: tropical depressions, tropical storms, hurricanes and typhoons.
When it comes to determining the severity of a tropical cyclone, wind speed plays a significant role -- though severe winds are not the only dangerous hazards produced by such weather events.
Here’s how they four tropical cyclones are classified:
- Tropical depression: The weakest type of tropical cyclone. Sustained wind speeds are below 39 mph.
- Tropical storm: An upgrade from a tropical depression. Sustained wind speeds are between 39-74 mph.
- Hurricane: An upgrade from a tropical storm. Sustained wind speeds are at 74 mph or higher. Hurricanes are placed into one of five categories depending on the sustained wind speeds they produce. A Category 5 hurricane is the most dangerous hurricane. Hurricanes occur in the north Atlantic Ocean, central north Pacific Ocean and the eastern north Pacific Ocean.
- Typhoon: A typhoon is the same thing as a hurricane. Wind speeds are at 74 mph or higher. The only difference between a typhoon and a hurricane is the location where it occurs. When a “hurricane” occurs in the northwest Pacific Ocean, it is called a typhoon.
In the south Pacific Ocean and the Indian Ocean, the term “tropical cyclone” is used to identify any type of tropical cyclone event, regardless of the strength of the storm or its winds.
“The ingredients for tropical cyclones include a pre-existing weather disturbance, warm tropical oceans, moisture, and relatively light winds. If the right conditions persist long enough, they can combine to produce the violent winds, large waves, torrential rains, and floods we associate with this phenomenon,” the NOS says.
A monsoon is not a one-off weather event that brings a lot of rain; it’s a bit more complex than that.
A monsoon is not a storm, rather it is a “seasonal change in direction” of the “strongest winds of a region,” experts say. Monsoons primarily affect the Indian Ocean and land regions bordering it.
There are two different types of monsoons: The summer monsoon and the winter monsoon.
The summer monsoon, which typically occurs between April and September, brings moist air from the southwest Indian Ocean to countries like India, Sri Lanka, Bangladesh and Myanmar. This warm wind creates humid air and brings torrential rainfall to the region, which often causes flooding.
Nations depend on the heavy rains that fall during the summer monsoon, but heavy summer monsoons can be deadly, causing severe flooding and devastating damage to cities and rural areas.
The winter monsoon, which occurs between October and April, typically blows drier air to the region from northwestern China and Mongolia -- though that air does not reach all nations near the ocean. Winter monsoons are not as powerful, or deadly, as summer monsoons.
A tsunami is not a storm and does not require heavy rains to flood coastal communities.
A tsunami is a natural weather event caused by earthquakes or undersea volcanic eruptions. Earthquakes or undersea volcanic eruptions can trigger a series of giant waves that build higher and higher as they reach the coast.
When a tsunami occurs, those extremely long waves ripple out in all directions, and move through the entire water column (from ocean floor to surface). Wind-driven waves only travel on the top-most layer of the ocean.
Those tsunami waves can move incredibly fast, and can be devastating to coastal and inland communities -- though that’s not always the case.
Because a tsunami can occur so quickly and without much warning, tsunami waves “typically cause the most severe damage and casualties near their source,” according to the National Oceanic and Atmospheric Administration. Tsunami waves can travel as fast as jet planes over deep waters, but slow down once they reach shallow waters.
Tsunamis are only really dangerous when they reach land. Experts say that most tsunami waves are less than 10 feet high when they reach land, but those waves can reach 100 feet in extreme cases.
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