Hurricanes affect a lot of people deeply. How does wind accumulate and become fast spinning hurricanes and create so much damage? Let’s dive into how hurricanes form and operate - it can help people understand how to respond to them better.
Hurricanes depend on three things in order to form. These are predictable, measurable things that allow meteorologists to predict the size, strength, and path of hurricanes pretty accurately:
1. Ocean temperature
Ocean heat is the energy driver of hurricanes. Heat energy is a powerful energy when it is gathered over a massive area like the ocean. Ocean heat produces many thousands of times more energy than humans produce, planet wide.
One single average hurricane gathers, moves and releases this heat energy to the equivalent of around 200 times the world's total electrical generating capacity! Imagine the forces that are needed to create that much energy!
The ocean needs to be at least 79 F (26 C) before it can generate enough heat energy to feed and sustain a hurricane. In the Gulf, temperatures have been well above 79 F this season. The warmer the ocean is, the faster hurricanes can form and the stronger/bigger they can get.
One thing to bear in mind with ocean temperature is that oceans are the heatsink of the planet. The lower temperatures of the oceans absorb the heat in the air in an attempt to reach an equilibrium with it. All excess heat (over average) goes into the ocean where it stays until released during the cooler winter months.
There are a multitude of temperature layers as you go deeper and deeper. Each provides an environment for different species. As the planet temperature goes up there is more warm ocean water closer to the surface providing the first needed condition to breed hurricanes.
The ocean also needs to be hot at least 50 meters (164 feet) in depth. That is a massive LOT of heat energy. The shallow Gulf is an ideal place for water to heat up to that depth but any ocean in the tropics band can do so.
When a hurricane moves over cooler water or land, it loses strength. Thus, the ocean needs to be hot all along the pathway of the hurricane which can be hundreds of miles. Imagine how many units of heat energy are needed to keep a hurricane going along that massive pathway!
2. Moisture
When there is sufficient moisture in the air, it evaporates and rises and creates strong winds as well as a massive storm build up. We've all experienced thunderstorms that act like this, creating massive cloud build up, sometimes very rapidly.
But when this happens over warm oceans, the storm can integrate in ways that it can't over land. Heat transfer between water and air is much easier to accomplish as air and water are both in a state of fluid. Heat and moisture flows easily between them.
If dry air moves in on a hurricane, it can take some power from it. If there is enough dry air early on, it can prevent a hurricane from forming. If the air remains moist, the hurricane can continue to build.
3. Wind
A hurricane spins because of the effect of the earth as it turns (called Coriolis effect). That intense spin on such a large scale can only happen over open ocean. The wind power that drives the spin is generated by the rising heat exchanges going on amidst massive evaporation (see "moisture" above).
The planet has predictable large wind patterns created by its revolutions, like the trade winds and the Jet Stream. These large wind patterns plus temperatures and other factors cause wind patterns lower in the atmosphere. These patterns are regularly changing but in somewhat predictable ways.
Wind moving in the same direction of the hurricane allows it to form and strengthen. If wind patterns move against it or perpendicular (called "wind shear"), they can sap the strength or prevent a hurricane from forming.
Wind direction is determined by these global wind patterns (like trade winds that generally send hurricanes west from Africa), by the turning of the earth (Coreolis effect), and by high or low pressure (pressure systems sometimes send hurricanes north in the Atlantic, and in various directions in the Caribbean). These are all measurable and thus hurricane direction can be predicted.Hurricanes generally move from east to west in the Atlantic and Pacific because of trade winds unless a high pressure system sends them north. But in the Caribbean and eastern Pacific, multiple forces can send hurricanes in different directions.
Summary
Three things are needed for a hurricane to form and strengthen:
Warm ocean (79 F+)
Moist air
Favorable wind patterns
Three things that interfere with a hurricane, and can either stop or weaken it depending on volume:
Cooler ocean or land (less than 79 F)
Dry air
Wind that moves against the hurricane
Note that ALL of these factors are massive planetary systems, and that is what is necessary to produce a powerful hurricane. We have:
Sun energyOcean heat gain over hundreds of square miles
Forces created by planetary revolution (Coriolis effect)Planet wide upper and lower atmosphere wind patterns
Massive amounts of moisture in the air and ocean
These are not something that humans are capable of replicating. Again, a single hurricane produces 200X what all of our utility companies produce worldwide. We do not have the technology or resources to create or control this amount of energy which is equivalent to numerous nuclear bombs every few minutes.
The planet, however, has no problem creating these beasts and has done so for eons. If there are more of them or they are more powerful, it is because one or more of the above factors are increasing. We know ocean temperatures are increasing as part of climate change.
Anybody who has been through a hurricane and its aftermath has witnessed the force of this energy. Irma knocked big trees down across the entire state of Florida. Helene caused massive flooding and wind damage in six states because there was massive moisture in the air along with sufficient time over the very warm ocean for her to pull it up, and then wind patterns/pressure systems sent a good chunk of it up into Appalachia. These factors were analyzed and predicted by meteorologists across the country (and world). We have invented nothing that even comes close to that power - which ultimately sources from sun energy.
The reason hurricane strength and direction can be forecast as accurately as we do is because meteorologists can track ocean temperature, moisture in the air, and wind patterns pretty darn accurately and thus have good predictions on how strong a hurricane will get, and why. Much of this (temp, moisture, wind) data is provided by NOAA and other similar agencies around the world on a large/broad scale, but local weather stations also track these things and many people have their own backyard weather stations that share humidity, wind speed/direction and temperature. Backyard weather stations don’t predict hurricanes, but the point is, measuring the factors involved (heat, humidity, wind) is not rocket science!
Some factors are more variable than others, including how the hurricane's own power might affect its direction. Thus, the cone of uncertainty.
I'm posting this because of the various conspiracy theories running around right now about the formation of hurricanes. Many people have never studied thermodynamics (heat energy), atmospheric science (including wind/moisture/heat/chemistry, etc) or meteorology (study of short term weather events). I never studied these much until I got into weather as an adult hobby.
I encourage anybody interested to study them - they are fascinating topics (imo). I am not an expert in any of these, but the basics are all you need in order to understand why hurricanes get stronger or move in a certain direction. The laws of thermodynamics are observable and can be replicated by you as an individual as well (including heat energy release from evaporation - just wave your hand over a pot of boiling water or consider a steam engine). Again, fascinating stuff!
In permaculture (whole systems design), we design systems, whether in your backyard or village scale or for a bioregion, from pattern to detail. A significant pattern that affects all of us is patterns found in weather and climate. Understanding the forces that create weather can help us all design more resilient systems.
If you found this useful, please feel free to share. How weather works is a fascinating subject and has so much to do with our lives!
Stay tuned for more info on how hurricanes help our gardens, how to minimize the damage from them, and more disaster response and prepping from a permaculture perspective.
I quickly read this as I sit here in my home on Tampa Bay. Thank you so much for sharing because it helps to understand the environmental conditions that we take for granted but don't fully understand. We were very fortunate to have minimal damage when others around us have lost so much. So, I will forward this to friends and neighbors that ask why. I trust that you are well and safe following this shared weather event here in Florida. Best!