The Hurricane Season is upon us once again, with forecasts showing above-normal activity for 2022. While we often hear the message of preparedness and how climate change is intensifying hurricane activity, have you ever thought about what causes hurricanes?
Look no further, let’s dive into all things hurricane.
What is a Hurricane?
The National Oceanic and Atmospheric Administration simply explains that a hurricane is a tropical cyclone – a type of storm – which forms over tropical or subtropical waters. A tropical cyclone is a rotating low-pressure weather system with organized thunderstorms but no fronts (the boundary separating two air masses of different densities).
Hurricanes originate in the Atlantic basin comprising the Atlantic Ocean, the Caribbean Sea, the Gulf of Mexico, the eastern North Pacific Ocean, and on a lesser scale the central North Pacific Ocean. A storm has officially upgraded to a hurricane when maximum sustained winds reach 74 mph.
What causes Hurricanes?
Hurricanes thrive on warmth in every sense, which is why global warming has been a driver for above-normal activity each season. Warm water, moist warm air, and light upper-level winds converge to create hurricanes. According to Earth Eclipse, here is how a hurricane forms in the ocean:
Hurricanes begin to form when masses of warm, moist air from oceans’ surfaces rise quickly and collide with masses of cooler air. The collision prompts warm water vapor to condense, leading to the formation of storm clouds and dropping back as rain.
As the process goes on, more warm moist air is attracted into the mounting storm, and much more heat is moved from the ocean surface to the atmosphere. This constant heat exchange develops a wind pattern that spins around the center that mimics water spinning down a drain.
If conditions remain the same, the rotating storm will continue to get powerful, eventually becoming a hurricane. As the hurricane continues to strengthen, a clear circular opening at the center known as the eye forms.
The strongest winds occur near the eye, which means the winds get strong as you approach the eye. The eye wall is the area surrounding the eye, and it has much stronger winds than the eye. When a stronger hurricane develops, winds can reach speeds of up to 200 miles per hour. If the storms lose energy, it means they have reached cooler waters or hit the shores, and they start to weaken and eventually die off.
There are three main stages winds transition through as storms develop into hurricanes:
1. Tropical depression: Wind speeds below 38 mph or 61.15 kph
2. Tropical Storm: Winds speeds ranging from 39 mph to 73 mph or 62.76 kph to 117.48 kph
3. Hurricane: Winds speed over 74 mph or 119.09 kph
What makes up a Hurricane?
1. The Eye is the core of the hurricane, with an average diameter of 20-40 miles. The inside of the eye is characterized by calm winds, clear skies, and low air pressure.
2. The Eye Wall surrounds the eye and harbors the most powerful and destructive winds. The heaviest rains are formed at the eye wall.
3. Rain Bands are a collection of dense clouds which form a spiral around the eye wall. They are responsible for the pinwheel resemblance of hurricanes. The bands average 50-300 miles.