The word cyclone refers to many different types of storms. In this video lesson you will learn about how cyclones form, what makes each type different, and what their effects are on both people and the environment.
What Are Cyclones?
Location, location, location! This is especially important when we’re talking about ocean storms because the location of the storm determines what we call it. For example, if the storm occurs in the Atlantic Ocean and Northeast Pacific, it’s called a hurricane. If the exact same type of storm occurs in the Northwest Pacific, this is a typhoon. And if we find those same storms in the South Pacific and Indian Ocean, these are called tropical cyclones.
Cyclone refers to any spinning storm that rotates around a low-pressure center. The low-pressure center is also referred to as the ‘eye’ of the storm, which is well known for being eerily calm compared with the areas under the spinning ‘arms’ of the storm. You could say that the eye is watching what’s going on down below, so it needs a clear path, but the arms are where all the action happens because this is where the storm is throwing out all of its rain and wind.
Types of Cyclones
The term ‘cyclone’ actually refers to several different types of storms. They occur in different places, and some occur over land while others occur over water. What they all have in common is that they are spinning storms rotating around that low-pressure center.
Tropical cyclones are what most people are familiar with because these are cyclones that occur over tropical ocean regions. Hurricanes and typhoons are actually types of tropical cyclones, but they have different names so that it’s clear where that storm is occurring. Hurricanes are found in the Atlantic and Northeast Pacific, typhoons are found in the Northwest Pacific. If you hear ‘tropical cyclone,’ you should assume that it’s occurring in the South Pacific or Indian Ocean, but for this lesson, we’ll use it refer to all types of tropical ocean cyclones.
We can also further describe tropical cyclones based on their wind speeds. They are called category 1, 2, 3, 4 or 5, increasing with intensity and wind speed as the number increases. A category 1 cyclone is the weakest, with wind speeds of 74-95 mph. A category 5 cyclone, on the other hand, is extremely dangerous and has the potential for major damage. Category 5 cyclones have wind speeds of 155 mph and above!Polar cyclones are cyclones that occur in polar regions like Greenland, Siberia and Antarctica.
Unlike tropical cyclones, polar cyclones are usually stronger in winter months. As you can see, these storms really do prefer the colder weather! They also occur in areas that aren’t very populated, so any damage they do is usually pretty minimal.A mesocyclone is when part of a thunderstorm cloud starts to spin, which may eventually lead to a tornado. ‘Meso’ means ‘middle’, so you can think of this as the mid-point between one type of storm and the other. Tornadoes all come from thunderstorm clouds, but not all thunderstorm clouds make tornadoes. In order for a tornado to occur, part of that cloud has to spin, and though you can’t really see this happening, this is the intermediate, or ‘meso’ step from regular cloud to dangerous spinning cloud running along the ground.
Formation of a Cyclone
Even though they form over different areas, cyclones tend to come about in the same way and revolve around that low-pressure eye.
Warm air likes to rise, and as it rises, it cools. Cool air can’t hold as much moisture as warm air, so that water gets squeezed out of the condensing air and a cloud begins to form. If the warm air rises very quickly, this creates an updraft.Likewise, if the water in the cloud builds up enough, it may fall back to the ground as rain and draw cool air down with it as a downdraft. When they work together, that warm updraft and cool downdraft create a storm cell. As this process continues, the cloud grows and we eventually get a large thunderstorm cloud.
This thunderstorm cloud is now ready to diversify into other storms like tropical cyclones and tornadoes. But this can’t happen unless the air in the cloud starts spinning horizontally. If this occurs over the tropical ocean, this is called a tropical depression. This is like a baby tropical cyclone, with wind speeds less than 39 mph.If it starts spinning even faster and has wind speeds between 40-73 mph, we have a tropical storm. If the storm grows even larger over the tropical ocean and has wind speeds above 74 mph, we have our full-grown hurricane, typhoon or cyclone, depending on where that storm is found.
If the spinning occurs over land, we now have our mesocyclone. If the mesocyclone gets spinning fast enough that the cloud starts reaching toward the ground like a long arm, this is the beginning of a tornado. If the cloud’s arm reaches all the way to the ground and grabs hold, this is now officially a tornado, ready to suck up everything in its path like a giant vacuum cleaner hose.
Effects of Cyclones
No matter what type of cyclone you are talking about, there is always a great potential for damage to human life, livelihoods and the environment.
Tornadoes have indiscriminate paths and the cyclones themselves can be several miles wide. They take no prisoners as they skate along the ground, destroying everything they come in contact with.Tropical cyclones not only bring strong winds but also torrential rains and storm surges.
A storm surge is like a giant wall of water that the storm pushes along the ocean as it travels, and it can literally wash away large buildings and shorelines when it hits land. The heavy rains from tropical cyclones can also cause flooding. The damage in New Orleans from Hurricane Katrina wasn’t so much from the storm itself as it was from the levees failing.
All that water had built up behind them and at some point, they just couldn’t hold it back any longer.
‘Cyclone’ can be a confusing word because it refers to many different types of storms. However, all cyclones are spinning storms that rotate around a low-pressure center. This means that hurricanes, typhoons and tornadoes are all types of cyclones.
What makes each cyclone unique is its location. Tornadoes occur over land, polar cyclones occur in polar regions and tropical cyclones occur over tropical oceans.What’s not unique is how these storms develop. Warm air rises, and it likes to take water along with it. When that warm, moist air rises quickly, we get an updraft.
However, cool air isn’t as fond of water as warm air, so the water in the air gets pushed out as the warm, rising air cools.This condensation forms a cloud in the sky, and if enough condensation builds up, it falls back to the ground. As the rain falls, cool air is drawn down with it as a downdraft.
When the updraft and downdraft team up, they form a thunderstorm cloud, which is like a diving board for cyclone formation.If the air in the cloud starts to spin horizontally, we have the beginnings of a cyclone. On land, this is a mesocyclone and over tropical oceans, this is a tropical depression. No matter what type of cyclone develops, they all have the power to inflict great damage. Tropical cyclones and tornadoes have literally wiped out cities and shorelines.
Even tropical storms (which are a mid-way point between a tropical depression and a tropical cyclone) can bring heavy rains, strong winds, storm surges and floods. These dangerous conditions may take lives, destroy livelihoods and even reshape landscapes as they spin along their paths.
When this lesson is done, you should be able to:
- Define the many storms called cyclones
- Describe how cyclones are formed
- List some of the effects cyclones can have on people and the environment