What a Study of Over 30 Years of Hurricane Eye Images Tells Us

By examining satellite imagery from 1982-2015 across ocean basins, the new historical record of tropical cyclone eyes was developed by NOAA scientist Ken Knapp and the Cooperative Institute for Meteorological Satellite Studies. To clear up any potential confusion, the term tropical cyclone includes what you more commonly might know as a hurricane in the Atlantic or a typhoon in the western Pacific Ocean.

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The research found that about 51 percent of the tropical cyclones in the 34-year period studied developed at least one eye during their existence. This was determined by using a computer algorithm to investigate a quarter million satellite images for various tropical cyclones in a global database called HURSAT, according to NOAA.

Storms that formed an eye typically held onto it for at least 30 hours. The longest lasting eye in the study belonged to Hurricane Ioke in the central Pacific Ocean which had one for 12 days in 2006.

The research also found that tropical cyclone eyes occurred more often in the Northern Hemisphere ocean basins. In Southern Hemisphere ocean basins, however, tropical cyclone eyes were found to be larger overall.

When it comes to how often eyes developed in each particular tropical cyclone basin, here's what the researchers found:

• Western Pacific: storms developed an eye 66 percent of the time
• Eastern Pacific: storms developed an eye 52 percent of the time
• North Indian Ocean: storms developed an eye 46 percent of the time
• South Indican Ocean: storms developed an eye 43 percent of the time
• North Atlantic Ocean: storms developed an eye 41 percent of the time
• South Pacific Ocean: storms developed an eye 40 percent of the time

The researchers also looked at how intensity relates to the formation of an eye in a tropical cyclone. They found that tropical cyclones with an eye had average wind speeds that were almost three times higher than those that lacked an eye.

"In the future, the scientists hope to incorporate additional satellite data from different instruments into the climatology to produce a consensus eye product," NOAA said.

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More About Hurricane Eyes

Some of the most dramatic weather changes on Earth can occur over a short distance near the eye of an intense hurricane.

Inside the eye, winds are mostly light. Lurking a short distance away lies the surrounding eyewall, where the most intense and destructive winds of a hurricane are found.

Hurricane eyes appear in various sizes and shapes. They can also vary in how they appear during the life of a hurricane.

A great example is Hurricane Wilma in 2005, which had a tiny eye that was just 2 nautical miles wide when it was a Category 5 hurricane in the northwest Caribbean. That tiny eye was replaced by another eye around a day later that was 40 nautical miles wide, according to the National Hurricane Center. The eye remained 40 to 60 nautical miles wide for the rest of Wilma's existence.

Some hurricane eyes are clear enough that portions of the ocean surface may be visible from satellite images, while others are filled with clouds. A person on the ground in the middle of an eye could see blue skies during the day or stars at night if the eye is free of widespread clouds.