Ask a Professor: Hurricane Winds

9/30/2022 7:53:10 AM

Frank Lombardo
Frank Lombardo

As news about Hurricane Ian continues to dominate headlines, civil and environmental engineering assistant professor Frank Lombardo answers a few questions about hurricane winds and the damage they cause.  Lombardo's expertise is in wind engineering, extreme wind characterization, bluff body aerodynamics, resilience and structural damage.

What type of wind damage can a community expect when a Category 1 hurricane hits? What about a Category 5?

For a Category 1 hurricane you might expect scattered damage in a community, generally minor roof damage, maybe sporadic power outages due to failed power lines. For a Category 5 a community may expect widespread and significant wind damage, including structural damage to the roof and walls. Power may be out for weeks. If in an area prone to storm surge (similar to some areas affected by Ian) a Category 5 can generate significant water-induced forces on the structure that can be much more dangerous than the wind.

What type of infrastructure changes could help mitigate the impacts of these types of storms?

Considering the wind only there are number of simple things one can do for houses. One is to harden your garage door. We found from research that homes that suffered damage to the garage door suffered a disproportionate amount of roof damage. This is due to internal pressure that is “let in” if the garage door fails. We as a society should give some thought about where we build and the risks associated with it.

Is there a difference in the type of wind damage caused by hurricanes vs tornadoes?

In short, yes. The wind fields are completely different in scale, duration and character. Tornado characteristics like large pressure drops over a small area and the vertical component of the wind can serve to create more damage for a specific wind speed. Although it hasn’t been quantified, debris seems to be more significant in tornadoes all other things being equal. Hurricane damage given its spatial scale tends to be more widespread and has wider-ranging impacts downstream (e.g., power outages). 

Has climate change played a role in the frequency or severity of hurricanes hitting the U.S.?

Yes. And future projections suggest the frequency and severity will continue to increase.

Lombardo's students set up equipment in advance of Hurricane Ian hitting land in order to collect research data.
Lombardo's students set up equipment in advance of Hurricane Ian hitting land in order to collect research data.

What are some of the projects your research group is working on, related to the impact of high winds on personal property and public infrastructure?

We work on both ends of the research spectrum when considering high winds. There is a significant lack of surface wind data in all extreme wind events. In hurricanes for example, most official weather stations lose power and do not record the highest winds. Understanding the relationship between wind speed and damage is critical to mitigate the damage and so we deploy our instruments before these events make landfall to collect vital wind data. In the days leading up to Ian, for example, several of the students from my research lab traveled to Florida to deploy two wind measurement towers and approximately 40 pressure sensors. When it is safe to return, they’ll collect the equipment and we'll begin analyzing the data to improve characterization of Ian's wind field and to correlate wind speeds with associated damage. Learning from the damage is also critical to mitigation and so after the event we assess the damage to the built and natural environment.


Editor's note:

To reach Frank Lombardo, email lombaf@illinois.edu