How Do Hurricanes Form?

Hurricanes are the most violent storms on Earth. People call these storms by other names, such as typhoons or cyclones, depending on where they occur.

The scientific term for ALL of these storms is tropical cyclone. Only tropical cyclones that form over the Atlantic Ocean or eastern and central Pacific Ocean are called “hurricanes.”

Whatever they are called, tropical cyclones all form the same way.

Tropical cyclones are like giant engines that use warm, moist air as fuel. That is why they form only over warm ocean waters near the equator. This warm, moist air rises and condenses to form clouds and storms.

As this warmer, moister air rises, there’s less air left near the Earth’s surface. Essentially, as this warm air rises, this causes an area of lower air pressure below.

This starts the ‘engine’ of the storm. To fill in the low pressure area, air from surrounding areas with higher air pressure pushes in. That “new” air near the Earth’s surface also gets heated by the warm ocean water so it also gets warmer and moister and then it rises.

As the warm air continues to rise, the surrounding air swirls in to take its place. The whole system of clouds and wind spins and grows, fed by the ocean’s heat and water evaporating from the surface.

As the storm system rotates faster and faster, an eye forms in the center. It is vey calm and clear in the eye, with very low air pressure.

Tropical cyclones usually weaken when they hit land, because they are no longer being “fed” by the energy from the warm ocean waters. However, when they move inland, they can drop many inches of rain causing flooding as well as wind damage before they die out completely. 

There are five types, or categories, of hurricanes. The scale of categories is called the Saffir-Simpson Hurricane Scale and they are based on wind speed.

How Does NASA Study Hurricanes?

Our satellites gather information from space that are made into pictures. Some satellite instruments measure cloud and ocean temperatures. Others measure the height of clouds and how fast rain is falling. Still others measure the speed and direction of winds.

We also fly airplanes into and above hurricanes. The instruments aboard planes gather details about the storm. Some parts are too dangerous for people to fly into. To study these parts, we use airplanes that operate without people. 

Learn more about this and other questions by exploring NASA Space Place and the NASA/NOAA SciJinks that offer explanations of science topics for school kids.

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Credits: NASA Space Place & NASA/NOAA SciJinks

Swirling bands of light and dark clouds on Jupiter are seen in this image made by citizen scientists using data from our Juno spacecraft. Each of the alternating light and dark atmospheric bands in this image is wider than Earth, and each rages around Jupiter at hundreds of miles (km) per hour. The lighter areas are regions where gas is rising, and the darker bands are regions where gas is sinking. This image was acquired on May 19, 2017 from about 20,800 miles (33,400km) above Jupiter’s cloud tops.

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Credits: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt /Seán Doran

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Ok, witches! I gotta tell you about meteorological symbols!

There’s one for every weather condition you can think of! You can probably find a longer list in the back of a dictionary, or just search Google images.

  • You can use them as sigils on their own, or use them as inspiration to make your own sigils!
  • Use them for weather summoning!
  • Use the symbols as a substitute for certain weather conditions! For example, if a spell calls for rainwater and you live in the desert, use the meteorological symbol for heavy rain.
  • Use the metaphorical attributes of the symbols in spells! For example, a hurricane for added energy, or fog for concealment.
  • The list goes on!
4

a few people (usually at gas stations, noting my hail destroyed car) have asked, “why do you storm chase” and the only good answer I have is “why don’t you?” 

it’s true I’m not a classical storm chaser. I tend to entirely different areas of the storm than most do (the part that still has some light if possible) and really, I’m a photographer chasing a photo more than a storm chaser but I can’t imagine why anyone wouldn’t want to scream across the prairie after some monster so big and alive you can hardly take it all in (even at 15mm). the complexity, drama, violence and power make almost anything possible. I’ve seen things that took my breath away, and cowered in my car praying my glass would hold and that nothing terribly nasty was living in that shroud of rain that pinned me to where I was. 

I’ve wasted entire days on hope. 

I hope that storm can organize itself despite all the science saying it can’t. I hope I can get to this spot on the map before it does. I hope the light holds. or the road hasn’t heaved too bad this winter. 

every year i commit myself to only chase the big bad boys that have structure, and form, and the rare magic of a fully formed super cell and every year I find myself rolling across the gravel roads after some pulse storm that maybe, just maybe has something pretty in it. 

so entering year three of really learning and chasing more seriously my answer would be, why aren’t you out there, living and dying with the gust fronts and hail cores and living creatures sucking up the prairie moist. really. why?